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<p class='location'>Trait Iterator</p><div class="block items"><ul><li><a href="#associated-types">Associated Types</a></li><li><a href="#required-methods">Required Methods</a></li><li><a href="#provided-methods">Provided Methods</a></li><li><a href="#implementors">Implementors</a></li></ul></div><p class='location'><a href='../index.html'>std</a>::<wbr><a href='index.html'>iter</a></p><script>window.sidebarCurrent = {name: 'Iterator', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<h1 class='fqn'><span class='in-band'>Trait <a href='../index.html'>std</a>::<wbr><a href='index.html'>iter</a>::<wbr><a class="trait" href=''>Iterator</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'>
<a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
[<span class='inner'>−</span>]
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</span><a class='srclink' href='../../src/core/iter/iterator.rs.html#31-2200' title='goto source code'>[src]</a></span></h1>
<pre class='rust trait'>pub trait Iterator {
type <a href='#associatedtype.Item' class="type">Item</a>;
fn <a href='#tymethod.next' class='fnname'>next</a>(&mut self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>;
fn <a href='#method.size_hint' class='fnname'>size_hint</a>(&self) -> <a class="primitive" href="../primitive.tuple.html">(</a><a class="primitive" href="../primitive.usize.html">usize</a>, <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.usize.html">usize</a>><a class="primitive" href="../primitive.tuple.html">)</a> { ... }
fn <a href='#method.count' class='fnname'>count</a>(self) -> <a class="primitive" href="../primitive.usize.html">usize</a> { ... }
fn <a href='#method.last' class='fnname'>last</a>(self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> { ... }
fn <a href='#method.nth' class='fnname'>nth</a>(&mut self, n: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> { ... }
fn <a href='#method.step_by' class='fnname'>step_by</a>(self, step: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="struct" href="../../std/iter/struct.StepBy.html" title="struct std::iter::StepBy">StepBy</a><Self> { ... }
fn <a href='#method.chain' class='fnname'>chain</a><U>(self, other: U) -> <a class="struct" href="../../std/iter/struct.Chain.html" title="struct std::iter::Chain">Chain</a><Self, <U as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIter</a>><br> <span class="where">where<br> U: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a><Item = Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>></span>,
{ ... }
fn <a href='#method.zip' class='fnname'>zip</a><U>(self, other: U) -> <a class="struct" href="../../std/iter/struct.Zip.html" title="struct std::iter::Zip">Zip</a><Self, <U as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIter</a>><br> <span class="where">where<br> U: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a></span>,
{ ... }
fn <a href='#method.map' class='fnname'>map</a><B, F>(self, f: F) -> <a class="struct" href="../../std/iter/struct.Map.html" title="struct std::iter::Map">Map</a><Self, F><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B</span>,
{ ... }
fn <a href='#method.filter' class='fnname'>filter</a><P>(self, predicate: P) -> <a class="struct" href="../../std/iter/struct.Filter.html" title="struct std::iter::Filter">Filter</a><Self, P><br> <span class="where">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a></span>,
{ ... }
fn <a href='#method.filter_map' class='fnname'>filter_map</a><B, F>(self, f: F) -> <a class="struct" href="../../std/iter/struct.FilterMap.html" title="struct std::iter::FilterMap">FilterMap</a><Self, F><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><B></span>,
{ ... }
fn <a href='#method.enumerate' class='fnname'>enumerate</a>(self) -> <a class="struct" href="../../std/iter/struct.Enumerate.html" title="struct std::iter::Enumerate">Enumerate</a><Self> { ... }
fn <a href='#method.peekable' class='fnname'>peekable</a>(self) -> <a class="struct" href="../../std/iter/struct.Peekable.html" title="struct std::iter::Peekable">Peekable</a><Self> { ... }
fn <a href='#method.skip_while' class='fnname'>skip_while</a><P>(self, predicate: P) -> <a class="struct" href="../../std/iter/struct.SkipWhile.html" title="struct std::iter::SkipWhile">SkipWhile</a><Self, P><br> <span class="where">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a></span>,
{ ... }
fn <a href='#method.take_while' class='fnname'>take_while</a><P>(self, predicate: P) -> <a class="struct" href="../../std/iter/struct.TakeWhile.html" title="struct std::iter::TakeWhile">TakeWhile</a><Self, P><br> <span class="where">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a></span>,
{ ... }
fn <a href='#method.skip' class='fnname'>skip</a>(self, n: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="struct" href="../../std/iter/struct.Skip.html" title="struct std::iter::Skip">Skip</a><Self> { ... }
fn <a href='#method.take' class='fnname'>take</a>(self, n: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="struct" href="../../std/iter/struct.Take.html" title="struct std::iter::Take">Take</a><Self> { ... }
fn <a href='#method.scan' class='fnname'>scan</a><St, B, F>(self, initial_state: St, f: F) -> <a class="struct" href="../../std/iter/struct.Scan.html" title="struct std::iter::Scan">Scan</a><Self, St, F><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&mut St, Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><B></span>,
{ ... }
fn <a href='#method.flat_map' class='fnname'>flat_map</a><U, F>(self, f: F) -> <a class="struct" href="../../std/iter/struct.FlatMap.html" title="struct std::iter::FlatMap">FlatMap</a><Self, U, F><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> U,<br> U: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a></span>,
{ ... }
fn <a href='#method.fuse' class='fnname'>fuse</a>(self) -> <a class="struct" href="../../std/iter/struct.Fuse.html" title="struct std::iter::Fuse">Fuse</a><Self> { ... }
fn <a href='#method.inspect' class='fnname'>inspect</a><F>(self, f: F) -> <a class="struct" href="../../std/iter/struct.Inspect.html" title="struct std::iter::Inspect">Inspect</a><Self, F><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.tuple.html">()</a></span>,
{ ... }
fn <a href='#method.by_ref' class='fnname'>by_ref</a>(&mut self) -> &mut Self { ... }
fn <a href='#method.collect' class='fnname'>collect</a><B>(self) -> B<br> <span class="where">where<br> B: <a class="trait" href="../../std/iter/trait.FromIterator.html" title="trait std::iter::FromIterator">FromIterator</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>></span>,
{ ... }
fn <a href='#method.partition' class='fnname'>partition</a><B, F>(self, f: F) -> <a class="primitive" href="../primitive.tuple.html">(</a>B, B<a class="primitive" href="../primitive.tuple.html">)</a><br> <span class="where">where<br> B: <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a> + <a class="trait" href="../../std/iter/trait.Extend.html" title="trait std::iter::Extend">Extend</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>,<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a></span>,
{ ... }
fn <a href='#method.fold' class='fnname'>fold</a><B, F>(self, init: B, f: F) -> B<br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(B, Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B</span>,
{ ... }
fn <a href='#method.all' class='fnname'>all</a><F>(&mut self, f: F) -> <a class="primitive" href="../primitive.bool.html">bool</a><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a></span>,
{ ... }
fn <a href='#method.any' class='fnname'>any</a><F>(&mut self, f: F) -> <a class="primitive" href="../primitive.bool.html">bool</a><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a></span>,
{ ... }
fn <a href='#method.find' class='fnname'>find</a><P>(&mut self, predicate: P) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>><br> <span class="where">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a></span>,
{ ... }
fn <a href='#method.position' class='fnname'>position</a><P>(&mut self, predicate: P) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.usize.html">usize</a>><br> <span class="where">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a></span>,
{ ... }
fn <a href='#method.rposition' class='fnname'>rposition</a><P>(&mut self, predicate: P) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.usize.html">usize</a>><br> <span class="where">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>,<br> Self: <a class="trait" href="../../std/iter/trait.ExactSizeIterator.html" title="trait std::iter::ExactSizeIterator">ExactSizeIterator</a> + <a class="trait" href="../../std/iter/trait.DoubleEndedIterator.html" title="trait std::iter::DoubleEndedIterator">DoubleEndedIterator</a></span>,
{ ... }
fn <a href='#method.max' class='fnname'>max</a>(self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>><br> <span class="where">where<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a></span>,
{ ... }
fn <a href='#method.min' class='fnname'>min</a>(self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>><br> <span class="where">where<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a></span>,
{ ... }
fn <a href='#method.max_by_key' class='fnname'>max_by_key</a><B, F>(self, f: F) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>><br> <span class="where">where<br> B: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>,<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B</span>,
{ ... }
fn <a href='#method.max_by' class='fnname'>max_by</a><F>(self, compare: F) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>, &Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/cmp/enum.Ordering.html" title="enum std::cmp::Ordering">Ordering</a></span>,
{ ... }
fn <a href='#method.min_by_key' class='fnname'>min_by_key</a><B, F>(self, f: F) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>><br> <span class="where">where<br> B: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>,<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B</span>,
{ ... }
fn <a href='#method.min_by' class='fnname'>min_by</a><F>(self, compare: F) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>><br> <span class="where">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>, &Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/cmp/enum.Ordering.html" title="enum std::cmp::Ordering">Ordering</a></span>,
{ ... }
fn <a href='#method.rev' class='fnname'>rev</a>(self) -> <a class="struct" href="../../std/iter/struct.Rev.html" title="struct std::iter::Rev">Rev</a><Self><br> <span class="where">where<br> Self: <a class="trait" href="../../std/iter/trait.DoubleEndedIterator.html" title="trait std::iter::DoubleEndedIterator">DoubleEndedIterator</a></span>,
{ ... }
fn <a href='#method.unzip' class='fnname'>unzip</a><A, B, FromA, FromB>(self) -> <a class="primitive" href="../primitive.tuple.html">(</a>FromA, FromB<a class="primitive" href="../primitive.tuple.html">)</a><br> <span class="where">where<br> FromA: <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a> + <a class="trait" href="../../std/iter/trait.Extend.html" title="trait std::iter::Extend">Extend</a><A>,<br> FromB: <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a> + <a class="trait" href="../../std/iter/trait.Extend.html" title="trait std::iter::Extend">Extend</a><B>,<br> Self: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = <a class="primitive" href="../primitive.tuple.html">(</a>A, B<a class="primitive" href="../primitive.tuple.html">)</a>></span>,
{ ... }
fn <a href='#method.cloned' class='fnname'>cloned</a><'a, T>(self) -> <a class="struct" href="../../std/iter/struct.Cloned.html" title="struct std::iter::Cloned">Cloned</a><Self><br> <span class="where">where<br> Self: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = &'a T>,<br> T: 'a + <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a></span>,
{ ... }
fn <a href='#method.cycle' class='fnname'>cycle</a>(self) -> <a class="struct" href="../../std/iter/struct.Cycle.html" title="struct std::iter::Cycle">Cycle</a><Self><br> <span class="where">where<br> Self: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a></span>,
{ ... }
fn <a href='#method.sum' class='fnname'>sum</a><S>(self) -> S<br> <span class="where">where<br> S: <a class="trait" href="../../std/iter/trait.Sum.html" title="trait std::iter::Sum">Sum</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>></span>,
{ ... }
fn <a href='#method.product' class='fnname'>product</a><P>(self) -> P<br> <span class="where">where<br> P: <a class="trait" href="../../std/iter/trait.Product.html" title="trait std::iter::Product">Product</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>></span>,
{ ... }
fn <a href='#method.cmp' class='fnname'>cmp</a><I>(self, other: I) -> <a class="enum" href="../../std/cmp/enum.Ordering.html" title="enum std::cmp::Ordering">Ordering</a><br> <span class="where">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a><Item = Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a></span>,
{ ... }
fn <a href='#method.partial_cmp' class='fnname'>partial_cmp</a><I>(self, other: I) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="enum" href="../../std/cmp/enum.Ordering.html" title="enum std::cmp::Ordering">Ordering</a>><br> <span class="where">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>></span>,
{ ... }
fn <a href='#method.eq' class='fnname'>eq</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a><br> <span class="where">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialEq.html" title="trait std::cmp::PartialEq">PartialEq</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>></span>,
{ ... }
fn <a href='#method.ne' class='fnname'>ne</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a><br> <span class="where">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialEq.html" title="trait std::cmp::PartialEq">PartialEq</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>></span>,
{ ... }
fn <a href='#method.lt' class='fnname'>lt</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a><br> <span class="where">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>></span>,
{ ... }
fn <a href='#method.le' class='fnname'>le</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a><br> <span class="where">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>></span>,
{ ... }
fn <a href='#method.gt' class='fnname'>gt</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a><br> <span class="where">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>></span>,
{ ... }
fn <a href='#method.ge' class='fnname'>ge</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a><br> <span class="where">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>></span>,
{ ... }
}</pre><div class='docblock'><p>An interface for dealing with iterators.</p>
<p>This is the main iterator trait. For more about the concept of iterators
generally, please see the <a href="index.html">module-level documentation</a>. In particular, you
may want to know how to <a href="index.html#implementing-iterator">implement <code>Iterator</code></a>.</p>
</div>
<h2 id='associated-types'>Associated Types</h2>
<div class='methods'>
<h3 id='associatedtype.Item' class='method'><span id='Item.t' class='invisible'><code>type <a href='#associatedtype.Item' class="type">Item</a></code></span></h3><div class='docblock'><p>The type of the elements being iterated over.</p>
</div></div>
<h2 id='required-methods'>Required Methods</h2>
<div class='methods'>
<h3 id='tymethod.next' class='method'><span id='next.v' class='invisible'><code>fn <a href='#tymethod.next' class='fnname'>next</a>(&mut self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>></code></span></h3><div class='docblock'><p>Advances the iterator and returns the next value.</p>
<p>Returns <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> when iteration is finished. Individual iterator
implementations may choose to resume iteration, and so calling <code>next()</code>
again may or may not eventually start returning <a href="../../std/option/enum.Option.html#variant.Some"><code>Some(Item)</code></a> again at some
point.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>();
<span class="comment">// A call to next() returns the next value...</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>), <span class="ident">iter</span>.<span class="ident">next</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>), <span class="ident">iter</span>.<span class="ident">next</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>), <span class="ident">iter</span>.<span class="ident">next</span>());
<span class="comment">// ... and then None once it's over.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">None</span>, <span class="ident">iter</span>.<span class="ident">next</span>());
<span class="comment">// More calls may or may not return None. Here, they always will.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">None</span>, <span class="ident">iter</span>.<span class="ident">next</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">None</span>, <span class="ident">iter</span>.<span class="ident">next</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter()%3B%0A%0A%2F%2F%20A%20call%20to%20next()%20returns%20the%20next%20value...%0Aassert_eq!(Some(%261)%2C%20iter.next())%3B%0Aassert_eq!(Some(%262)%2C%20iter.next())%3B%0Aassert_eq!(Some(%263)%2C%20iter.next())%3B%0A%0A%2F%2F%20...%20and%20then%20None%20once%20it's%20over.%0Aassert_eq!(None%2C%20iter.next())%3B%0A%0A%2F%2F%20More%20calls%20may%20or%20may%20not%20return%20None.%20Here%2C%20they%20always%20will.%0Aassert_eq!(None%2C%20iter.next())%3B%0Aassert_eq!(None%2C%20iter.next())%3B%0A%7D">Run</a></pre>
</div></div>
<h2 id='provided-methods'>Provided Methods</h2>
<div class='methods'>
<h3 id='method.size_hint' class='method'><span id='size_hint.v' class='invisible'><code>fn <a href='#method.size_hint' class='fnname'>size_hint</a>(&self) -> <a class="primitive" href="../primitive.tuple.html">(</a><a class="primitive" href="../primitive.usize.html">usize</a>, <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.usize.html">usize</a>><a class="primitive" href="../primitive.tuple.html">)</a></code></span></h3><div class='docblock'><p>Returns the bounds on the remaining length of the iterator.</p>
<p>Specifically, <code>size_hint()</code> returns a tuple where the first element
is the lower bound, and the second element is the upper bound.</p>
<p>The second half of the tuple that is returned is an <a href="../../std/option/enum.Option.html"><code>Option</code></a><code><</code><a href="../../std/primitive.usize.html"><code>usize</code></a><code>></code>.
A <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> here means that either there is no known upper bound, or the
upper bound is larger than <a href="../../std/primitive.usize.html"><code>usize</code></a>.</p>
<h1 id='implementation-notes' class='section-header'><a href='#implementation-notes'>Implementation notes</a></h1>
<p>It is not enforced that an iterator implementation yields the declared
number of elements. A buggy iterator may yield less than the lower bound
or more than the upper bound of elements.</p>
<p><code>size_hint()</code> is primarily intended to be used for optimizations such as
reserving space for the elements of the iterator, but must not be
trusted to e.g. omit bounds checks in unsafe code. An incorrect
implementation of <code>size_hint()</code> should not lead to memory safety
violations.</p>
<p>That said, the implementation should provide a correct estimation,
because otherwise it would be a violation of the trait's protocol.</p>
<p>The default implementation returns <code>(0, None)</code> which is correct for any
iterator.</p>
<h1 id='examples-1' class='section-header'><a href='#examples-1'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">3</span>, <span class="prelude-val">Some</span>(<span class="number">3</span>)), <span class="ident">iter</span>.<span class="ident">size_hint</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Alet%20iter%20%3D%20a.iter()%3B%0A%0Aassert_eq!((3%2C%20Some(3))%2C%20iter.size_hint())%3B%0A%7D">Run</a></pre>
<p>A more complex example:</p>
<pre class="rust rust-example-rendered">
<span class="comment">// The even numbers from zero to ten.</span>
<span class="kw">let</span> <span class="ident">iter</span> <span class="op">=</span> (<span class="number">0</span>..<span class="number">10</span>).<span class="ident">filter</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">%</span> <span class="number">2</span> <span class="op">==</span> <span class="number">0</span>);
<span class="comment">// We might iterate from zero to ten times. Knowing that it's five</span>
<span class="comment">// exactly wouldn't be possible without executing filter().</span>
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">10</span>)), <span class="ident">iter</span>.<span class="ident">size_hint</span>());
<span class="comment">// Let's add five more numbers with chain()</span>
<span class="kw">let</span> <span class="ident">iter</span> <span class="op">=</span> (<span class="number">0</span>..<span class="number">10</span>).<span class="ident">filter</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">%</span> <span class="number">2</span> <span class="op">==</span> <span class="number">0</span>).<span class="ident">chain</span>(<span class="number">15</span>..<span class="number">20</span>);
<span class="comment">// now both bounds are increased by five</span>
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">5</span>, <span class="prelude-val">Some</span>(<span class="number">15</span>)), <span class="ident">iter</span>.<span class="ident">size_hint</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0A%2F%2F%20The%20even%20numbers%20from%20zero%20to%20ten.%0Alet%20iter%20%3D%20(0..10).filter(%7Cx%7C%20x%20%25%202%20%3D%3D%200)%3B%0A%0A%2F%2F%20We%20might%20iterate%20from%20zero%20to%20ten%20times.%20Knowing%20that%20it's%20five%0A%2F%2F%20exactly%20wouldn't%20be%20possible%20without%20executing%20filter().%0Aassert_eq!((0%2C%20Some(10))%2C%20iter.size_hint())%3B%0A%0A%2F%2F%20Let's%20add%20five%20more%20numbers%20with%20chain()%0Alet%20iter%20%3D%20(0..10).filter(%7Cx%7C%20x%20%25%202%20%3D%3D%200).chain(15..20)%3B%0A%0A%2F%2F%20now%20both%20bounds%20are%20increased%20by%20five%0Aassert_eq!((5%2C%20Some(15))%2C%20iter.size_hint())%3B%0A%7D">Run</a></pre>
<p>Returning <code>None</code> for an upper bound:</p>
<pre class="rust rust-example-rendered">
<span class="comment">// an infinite iterator has no upper bound</span>
<span class="comment">// and the maximum possible lower bound</span>
<span class="kw">let</span> <span class="ident">iter</span> <span class="op">=</span> <span class="number">0</span>..;
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="ident">usize</span>::<span class="ident">max_value</span>(), <span class="prelude-val">None</span>), <span class="ident">iter</span>.<span class="ident">size_hint</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0A%2F%2F%20an%20infinite%20iterator%20has%20no%20upper%20bound%0A%2F%2F%20and%20the%20maximum%20possible%20lower%20bound%0Alet%20iter%20%3D%200..%3B%0A%0Aassert_eq!((usize%3A%3Amax_value()%2C%20None)%2C%20iter.size_hint())%3B%0A%7D">Run</a></pre>
</div><h3 id='method.count' class='method'><span id='count.v' class='invisible'><code>fn <a href='#method.count' class='fnname'>count</a>(self) -> <a class="primitive" href="../primitive.usize.html">usize</a></code></span></h3><div class='docblock'><p>Consumes the iterator, counting the number of iterations and returning it.</p>
<p>This method will evaluate the iterator until its <a href="#tymethod.next"><code>next</code></a> returns
<a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>. Once <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is encountered, <code>count()</code> returns the number of
times it called <a href="#tymethod.next"><code>next</code></a>.</p>
<h1 id='overflow-behavior' class='section-header'><a href='#overflow-behavior'>Overflow Behavior</a></h1>
<p>The method does no guarding against overflows, so counting elements of
an iterator with more than <a href="../../std/isize/constant.MAX.html"><code>usize::MAX</code></a> elements either produces the
wrong result or panics. If debug assertions are enabled, a panic is
guaranteed.</p>
<h1 id='panics' class='section-header'><a href='#panics'>Panics</a></h1>
<p>This function might panic if the iterator has more than <a href="../../std/isize/constant.MAX.html"><code>usize::MAX</code></a>
elements.</p>
<h1 id='examples-2' class='section-header'><a href='#examples-2'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">count</span>(), <span class="number">3</span>);
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">count</span>(), <span class="number">5</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Aassert_eq!(a.iter().count()%2C%203)%3B%0A%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%2C%204%2C%205%5D%3B%0Aassert_eq!(a.iter().count()%2C%205)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.last' class='method'><span id='last.v' class='invisible'><code>fn <a href='#method.last' class='fnname'>last</a>(self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>></code></span></h3><div class='docblock'><p>Consumes the iterator, returning the last element.</p>
<p>This method will evaluate the iterator until it returns <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>. While
doing so, it keeps track of the current element. After <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is
returned, <code>last()</code> will then return the last element it saw.</p>
<h1 id='examples-3' class='section-header'><a href='#examples-3'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">last</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">last</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">5</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Aassert_eq!(a.iter().last()%2C%20Some(%263))%3B%0A%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%2C%204%2C%205%5D%3B%0Aassert_eq!(a.iter().last()%2C%20Some(%265))%3B%0A%7D">Run</a></pre>
</div><h3 id='method.nth' class='method'><span id='nth.v' class='invisible'><code>fn <a href='#method.nth' class='fnname'>nth</a>(&mut self, n: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>></code></span></h3><div class='docblock'><p>Returns the <code>n</code>th element of the iterator.</p>
<p>Like most indexing operations, the count starts from zero, so <code>nth(0)</code>
returns the first value, <code>nth(1)</code> the second, and so on.</p>
<p>Note that all preceding elements, as well as the returned element, will be
consumed from the iterator. That means that the preceding elements will be
discarded, and also that calling <code>nth(0)</code> multiple times on the same iterator
will return different elements.</p>
<p><code>nth()</code> will return <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> if <code>n</code> is greater than or equal to the length of the
iterator.</p>
<h1 id='examples-4' class='section-header'><a href='#examples-4'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">nth</span>(<span class="number">1</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Aassert_eq!(a.iter().nth(1)%2C%20Some(%262))%3B%0A%7D">Run</a></pre>
<p>Calling <code>nth()</code> multiple times doesn't rewind the iterator:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="number">1</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">nth</span>(<span class="number">1</span>), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter()%3B%0A%0Aassert_eq!(iter.nth(1)%2C%20Some(%262))%3B%0Aassert_eq!(iter.nth(1)%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Returning <code>None</code> if there are less than <code>n + 1</code> elements:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">nth</span>(<span class="number">10</span>), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Aassert_eq!(a.iter().nth(10)%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.step_by' class='method'><span id='step_by.v' class='invisible'><code>fn <a href='#method.step_by' class='fnname'>step_by</a>(self, step: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="struct" href="../../std/iter/struct.StepBy.html" title="struct std::iter::StepBy">StepBy</a><Self></code></span></h3><div class='stability'><div class='stab unstable'><details><summary><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>iterator_step_by </code><a href="https://github.com/rust-lang/rust/issues/27741">#27741</a>)</summary><p>unstable replacement of Range::step_by</p>
</details></div></div><div class='docblock'><p>Creates an iterator starting at the same point, but stepping by
the given amount at each iteration.</p>
<p>Note that it will always return the first element of the range,
regardless of the step given.</p>
<h1 id='panics-1' class='section-header'><a href='#panics-1'>Panics</a></h1>
<p>The method will panic if the given step is <code>0</code>.</p>
<h1 id='examples-5' class='section-header'><a href='#examples-5'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="attribute">#<span class="op">!</span>[<span class="ident">feature</span>(<span class="ident">iterator_step_by</span>)]</span>
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">0</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">step_by</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">0</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">4</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Bfeature(iterator_step_by)%5D%0Afn%20main()%20%7B%0Alet%20a%20%3D%20%5B0%2C%201%2C%202%2C%203%2C%204%2C%205%5D%3B%0Alet%20mut%20iter%20%3D%20a.into_iter().step_by(2)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%260))%3B%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20Some(%264))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D&version=nightly">Run</a></pre>
</div><h3 id='method.chain' class='method'><span id='chain.v' class='invisible'><code>fn <a href='#method.chain' class='fnname'>chain</a><U>(self, other: U) -> <a class="struct" href="../../std/iter/struct.Chain.html" title="struct std::iter::Chain">Chain</a><Self, <U as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIter</a>> <span class="where fmt-newline">where<br> U: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a><Item = Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>, </span></code></span></h3><div class='docblock'><p>Takes two iterators and creates a new iterator over both in sequence.</p>
<p><code>chain()</code> will return a new iterator which will first iterate over
values from the first iterator and then over values from the second
iterator.</p>
<p>In other words, it links two iterators together, in a chain. 🔗</p>
<h1 id='examples-6' class='section-header'><a href='#examples-6'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a1</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">a2</span> <span class="op">=</span> [<span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a1</span>.<span class="ident">iter</span>().<span class="ident">chain</span>(<span class="ident">a2</span>.<span class="ident">iter</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">4</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">5</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">6</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a1%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Alet%20a2%20%3D%20%5B4%2C%205%2C%206%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a1.iter().chain(a2.iter())%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0Aassert_eq!(iter.next()%2C%20Some(%264))%3B%0Aassert_eq!(iter.next()%2C%20Some(%265))%3B%0Aassert_eq!(iter.next()%2C%20Some(%266))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Since the argument to <code>chain()</code> uses <a href="trait.IntoIterator.html"><code>IntoIterator</code></a>, we can pass
anything that can be converted into an <a href="trait.Iterator.html"><code>Iterator</code></a>, not just an
<a href="trait.Iterator.html"><code>Iterator</code></a> itself. For example, slices (<code>&[T]</code>) implement
<a href="trait.IntoIterator.html"><code>IntoIterator</code></a>, and so can be passed to <code>chain()</code> directly:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">s1</span> <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">s2</span> <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">s1</span>.<span class="ident">iter</span>().<span class="ident">chain</span>(<span class="ident">s2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">4</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">5</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">6</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20s1%20%3D%20%26%5B1%2C%202%2C%203%5D%3B%0Alet%20s2%20%3D%20%26%5B4%2C%205%2C%206%5D%3B%0A%0Alet%20mut%20iter%20%3D%20s1.iter().chain(s2)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0Aassert_eq!(iter.next()%2C%20Some(%264))%3B%0Aassert_eq!(iter.next()%2C%20Some(%265))%3B%0Aassert_eq!(iter.next()%2C%20Some(%266))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.zip' class='method'><span id='zip.v' class='invisible'><code>fn <a href='#method.zip' class='fnname'>zip</a><U>(self, other: U) -> <a class="struct" href="../../std/iter/struct.Zip.html" title="struct std::iter::Zip">Zip</a><Self, <U as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIter</a>> <span class="where fmt-newline">where<br> U: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>, </span></code></span></h3><div class='docblock'><p>'Zips up' two iterators into a single iterator of pairs.</p>
<p><code>zip()</code> returns a new iterator that will iterate over two other
iterators, returning a tuple where the first element comes from the
first iterator, and the second element comes from the second iterator.</p>
<p>In other words, it zips two iterators together, into a single one.</p>
<p>When either iterator returns <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>, all further calls to <a href="../../std/iter/trait.Iterator.html#tymethod.next"><code>next</code></a>
will return <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>.</p>
<h1 id='examples-7' class='section-header'><a href='#examples-7'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a1</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">a2</span> <span class="op">=</span> [<span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a1</span>.<span class="ident">iter</span>().<span class="ident">zip</span>(<span class="ident">a2</span>.<span class="ident">iter</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="kw-2">&</span><span class="number">1</span>, <span class="kw-2">&</span><span class="number">4</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="kw-2">&</span><span class="number">2</span>, <span class="kw-2">&</span><span class="number">5</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="kw-2">&</span><span class="number">3</span>, <span class="kw-2">&</span><span class="number">6</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a1%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Alet%20a2%20%3D%20%5B4%2C%205%2C%206%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a1.iter().zip(a2.iter())%3B%0A%0Aassert_eq!(iter.next()%2C%20Some((%261%2C%20%264)))%3B%0Aassert_eq!(iter.next()%2C%20Some((%262%2C%20%265)))%3B%0Aassert_eq!(iter.next()%2C%20Some((%263%2C%20%266)))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Since the argument to <code>zip()</code> uses <a href="trait.IntoIterator.html"><code>IntoIterator</code></a>, we can pass
anything that can be converted into an <a href="trait.Iterator.html"><code>Iterator</code></a>, not just an
<a href="trait.Iterator.html"><code>Iterator</code></a> itself. For example, slices (<code>&[T]</code>) implement
<a href="trait.IntoIterator.html"><code>IntoIterator</code></a>, and so can be passed to <code>zip()</code> directly:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">s1</span> <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">s2</span> <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">s1</span>.<span class="ident">iter</span>().<span class="ident">zip</span>(<span class="ident">s2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="kw-2">&</span><span class="number">1</span>, <span class="kw-2">&</span><span class="number">4</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="kw-2">&</span><span class="number">2</span>, <span class="kw-2">&</span><span class="number">5</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="kw-2">&</span><span class="number">3</span>, <span class="kw-2">&</span><span class="number">6</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20s1%20%3D%20%26%5B1%2C%202%2C%203%5D%3B%0Alet%20s2%20%3D%20%26%5B4%2C%205%2C%206%5D%3B%0A%0Alet%20mut%20iter%20%3D%20s1.iter().zip(s2)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some((%261%2C%20%264)))%3B%0Aassert_eq!(iter.next()%2C%20Some((%262%2C%20%265)))%3B%0Aassert_eq!(iter.next()%2C%20Some((%263%2C%20%266)))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p><code>zip()</code> is often used to zip an infinite iterator to a finite one.
This works because the finite iterator will eventually return <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>,
ending the zipper. Zipping with <code>(0..)</code> can look a lot like <a href="trait.Iterator.html#method.enumerate"><code>enumerate</code></a>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">enumerate</span>: <span class="ident">Vec</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="string">"foo"</span>.<span class="ident">chars</span>().<span class="ident">enumerate</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">zipper</span>: <span class="ident">Vec</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> (<span class="number">0</span>..).<span class="ident">zip</span>(<span class="string">"foo"</span>.<span class="ident">chars</span>()).<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">0</span>, <span class="string">'f'</span>), <span class="ident">enumerate</span>[<span class="number">0</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">0</span>, <span class="string">'f'</span>), <span class="ident">zipper</span>[<span class="number">0</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">1</span>, <span class="string">'o'</span>), <span class="ident">enumerate</span>[<span class="number">1</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">1</span>, <span class="string">'o'</span>), <span class="ident">zipper</span>[<span class="number">1</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">2</span>, <span class="string">'o'</span>), <span class="ident">enumerate</span>[<span class="number">2</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>((<span class="number">2</span>, <span class="string">'o'</span>), <span class="ident">zipper</span>[<span class="number">2</span>]);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20enumerate%3A%20Vec%3C_%3E%20%3D%20%22foo%22.chars().enumerate().collect()%3B%0A%0Alet%20zipper%3A%20Vec%3C_%3E%20%3D%20(0..).zip(%22foo%22.chars()).collect()%3B%0A%0Aassert_eq!((0%2C%20'f')%2C%20enumerate%5B0%5D)%3B%0Aassert_eq!((0%2C%20'f')%2C%20zipper%5B0%5D)%3B%0A%0Aassert_eq!((1%2C%20'o')%2C%20enumerate%5B1%5D)%3B%0Aassert_eq!((1%2C%20'o')%2C%20zipper%5B1%5D)%3B%0A%0Aassert_eq!((2%2C%20'o')%2C%20enumerate%5B2%5D)%3B%0Aassert_eq!((2%2C%20'o')%2C%20zipper%5B2%5D)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.map' class='method'><span id='map.v' class='invisible'><code>fn <a href='#method.map' class='fnname'>map</a><B, F>(self, f: F) -> <a class="struct" href="../../std/iter/struct.Map.html" title="struct std::iter::Map">Map</a><Self, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B, </span></code></span></h3><div class='docblock'><p>Takes a closure and creates an iterator which calls that closure on each
element.</p>
<p><code>map()</code> transforms one iterator into another, by means of its argument:
something that implements <code>FnMut</code>. It produces a new iterator which
calls this closure on each element of the original iterator.</p>
<p>If you are good at thinking in types, you can think of <code>map()</code> like this:
If you have an iterator that gives you elements of some type <code>A</code>, and
you want an iterator of some other type <code>B</code>, you can use <code>map()</code>,
passing a closure that takes an <code>A</code> and returns a <code>B</code>.</p>
<p><code>map()</code> is conceptually similar to a <a href="../../book/first-edition/loops.html#for"><code>for</code></a> loop. However, as <code>map()</code> is
lazy, it is best used when you're already working with other iterators.
If you're doing some sort of looping for a side effect, it's considered
more idiomatic to use <a href="../../book/first-edition/loops.html#for"><code>for</code></a> than <code>map()</code>.</p>
<h1 id='examples-8' class='section-header'><a href='#examples-8'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="number">2</span> <span class="op">*</span> <span class="ident">x</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">4</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">6</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().map(%7Cx%7C%202%20*%20x)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(2))%3B%0Aassert_eq!(iter.next()%2C%20Some(4))%3B%0Aassert_eq!(iter.next()%2C%20Some(6))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>If you're doing some sort of side effect, prefer <a href="../../book/first-edition/loops.html#for"><code>for</code></a> to <code>map()</code>:</p>
<pre class="rust rust-example-rendered">
<span class="comment">// don't do this:</span>
(<span class="number">0</span>..<span class="number">5</span>).<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">x</span>));
<span class="comment">// it won't even execute, as it is lazy. Rust will warn you about this.</span>
<span class="comment">// Instead, use for:</span>
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="number">0</span>..<span class="number">5</span> {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">x</span>);
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused_must_use)%5D%0Afn%20main()%20%7B%0A%2F%2F%20don't%20do%20this%3A%0A(0..5).map(%7Cx%7C%20println!(%22%7B%7D%22%2C%20x))%3B%0A%0A%2F%2F%20it%20won't%20even%20execute%2C%20as%20it%20is%20lazy.%20Rust%20will%20warn%20you%20about%20this.%0A%0A%2F%2F%20Instead%2C%20use%20for%3A%0Afor%20x%20in%200..5%20%7B%0A%20%20%20%20println!(%22%7B%7D%22%2C%20x)%3B%0A%7D%0A%7D">Run</a></pre>
</div><h3 id='method.filter' class='method'><span id='filter.v' class='invisible'><code>fn <a href='#method.filter' class='fnname'>filter</a><P>(self, predicate: P) -> <a class="struct" href="../../std/iter/struct.Filter.html" title="struct std::iter::Filter">Filter</a><Self, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></span></h3><div class='docblock'><p>Creates an iterator which uses a closure to determine if an element
should be yielded.</p>
<p>The closure must return <code>true</code> or <code>false</code>. <code>filter()</code> creates an
iterator which calls this closure on each element. If the closure
returns <code>true</code>, then the element is returned. If the closure returns
<code>false</code>, it will try again, and call the closure on the next element,
seeing if it passes the test.</p>
<h1 id='examples-9' class='section-header'><a href='#examples-9'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">0i32</span>, <span class="number">1</span>, <span class="number">2</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">filter</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">is_positive</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B0i32%2C%201%2C%202%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().filter(%7Cx%7C%20x.is_positive())%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Because the closure passed to <code>filter()</code> takes a reference, and many
iterators iterate over references, this leads to a possibly confusing
situation, where the type of the closure is a double reference:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">0</span>, <span class="number">1</span>, <span class="number">2</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">filter</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">x</span> <span class="op">></span> <span class="number">1</span>); <span class="comment">// need two *s!</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B0%2C%201%2C%202%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().filter(%7Cx%7C%20**x%20%3E%201)%3B%20%2F%2F%20need%20two%20*s!%0A%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>It's common to instead use destructuring on the argument to strip away
one:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">0</span>, <span class="number">1</span>, <span class="number">2</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">filter</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="ident">x</span> <span class="op">></span> <span class="number">1</span>); <span class="comment">// both & and *</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B0%2C%201%2C%202%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().filter(%7C%26x%7C%20*x%20%3E%201)%3B%20%2F%2F%20both%20%26%20and%20*%0A%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>or both:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">0</span>, <span class="number">1</span>, <span class="number">2</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">filter</span>(<span class="op">|</span><span class="op">&&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">></span> <span class="number">1</span>); <span class="comment">// two &s</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B0%2C%201%2C%202%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().filter(%7C%26%26x%7C%20x%20%3E%201)%3B%20%2F%2F%20two%20%26s%0A%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>of these layers.</p>
</div><h3 id='method.filter_map' class='method'><span id='filter_map.v' class='invisible'><code>fn <a href='#method.filter_map' class='fnname'>filter_map</a><B, F>(self, f: F) -> <a class="struct" href="../../std/iter/struct.FilterMap.html" title="struct std::iter::FilterMap">FilterMap</a><Self, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><B>, </span></code></span></h3><div class='docblock'><p>Creates an iterator that both filters and maps.</p>
<p>The closure must return an <a href="../../std/option/enum.Option.html"><code>Option<T></code></a>. <code>filter_map</code> creates an
iterator which calls this closure on each element. If the closure
returns <a href="../../std/option/enum.Option.html#variant.Some"><code>Some(element)</code></a>, then that element is returned. If the
closure returns <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>, it will try again, and call the closure on the
next element, seeing if it will return <a href="../../std/option/enum.Option.html#variant.Some"><code>Some</code></a>.</p>
<p>Why <code>filter_map</code> and not just <a href="#method.filter"><code>filter</code></a>.<a href="#method.map"><code>map</code></a>? The key is in this
part:</p>
<blockquote>
<p>If the closure returns <a href="../../std/option/enum.Option.html#variant.Some"><code>Some(element)</code></a>, then that element is returned.</p>
</blockquote>
<p>In other words, it removes the <a href="../../std/option/enum.Option.html"><code>Option<T></code></a> layer automatically. If your
mapping is already returning an <a href="../../std/option/enum.Option.html"><code>Option<T></code></a> and you want to skip over
<a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>s, then <code>filter_map</code> is much, much nicer to use.</p>
<h1 id='examples-10' class='section-header'><a href='#examples-10'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="string">"1"</span>, <span class="string">"2"</span>, <span class="string">"lol"</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">filter_map</span>(<span class="op">|</span><span class="ident">s</span><span class="op">|</span> <span class="ident">s</span>.<span class="ident">parse</span>().<span class="ident">ok</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B%221%22%2C%20%222%22%2C%20%22lol%22%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter().filter_map(%7Cs%7C%20s.parse().ok())%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(1))%3B%0Aassert_eq!(iter.next()%2C%20Some(2))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Here's the same example, but with <a href="#method.filter"><code>filter</code></a> and <a href="#method.map"><code>map</code></a>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="string">"1"</span>, <span class="string">"2"</span>, <span class="string">"lol"</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>()
.<span class="ident">map</span>(<span class="op">|</span><span class="ident">s</span><span class="op">|</span> <span class="ident">s</span>.<span class="ident">parse</span>().<span class="ident">ok</span>())
.<span class="ident">filter</span>(<span class="op">|</span><span class="ident">s</span><span class="op">|</span> <span class="ident">s</span>.<span class="ident">is_some</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="prelude-val">Some</span>(<span class="number">1</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="prelude-val">Some</span>(<span class="number">2</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B%221%22%2C%20%222%22%2C%20%22lol%22%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.map(%7Cs%7C%20s.parse().ok())%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.filter(%7Cs%7C%20s.is_some())%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(Some(1)))%3B%0Aassert_eq!(iter.next()%2C%20Some(Some(2)))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>There's an extra layer of <a href="../../std/option/enum.Option.html#variant.Some"><code>Some</code></a> in there.</p>
</div><h3 id='method.enumerate' class='method'><span id='enumerate.v' class='invisible'><code>fn <a href='#method.enumerate' class='fnname'>enumerate</a>(self) -> <a class="struct" href="../../std/iter/struct.Enumerate.html" title="struct std::iter::Enumerate">Enumerate</a><Self></code></span></h3><div class='docblock'><p>Creates an iterator which gives the current iteration count as well as
the next value.</p>
<p>The iterator returned yields pairs <code>(i, val)</code>, where <code>i</code> is the
current index of iteration and <code>val</code> is the value returned by the
iterator.</p>
<p><code>enumerate()</code> keeps its count as a <a href="../../std/primitive.usize.html"><code>usize</code></a>. If you want to count by a
different sized integer, the <a href="#method.zip"><code>zip</code></a> function provides similar
functionality.</p>
<h1 id='overflow-behavior-1' class='section-header'><a href='#overflow-behavior-1'>Overflow Behavior</a></h1>
<p>The method does no guarding against overflows, so enumerating more than
<a href="../../std/usize/constant.MAX.html"><code>usize::MAX</code></a> elements either produces the wrong result or panics. If
debug assertions are enabled, a panic is guaranteed.</p>
<h1 id='panics-2' class='section-header'><a href='#panics-2'>Panics</a></h1>
<p>The returned iterator might panic if the to-be-returned index would
overflow a <a href="../../std/primitive.usize.html"><code>usize</code></a>.</p>
<h1 id='examples-11' class='section-header'><a href='#examples-11'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="string">'a'</span>, <span class="string">'b'</span>, <span class="string">'c'</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="number">0</span>, <span class="kw-2">&</span><span class="string">'a'</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="number">1</span>, <span class="kw-2">&</span><span class="string">'b'</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="number">2</span>, <span class="kw-2">&</span><span class="string">'c'</span>)));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B'a'%2C%20'b'%2C%20'c'%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter().enumerate()%3B%0A%0Aassert_eq!(iter.next()%2C%20Some((0%2C%20%26'a')))%3B%0Aassert_eq!(iter.next()%2C%20Some((1%2C%20%26'b')))%3B%0Aassert_eq!(iter.next()%2C%20Some((2%2C%20%26'c')))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.peekable' class='method'><span id='peekable.v' class='invisible'><code>fn <a href='#method.peekable' class='fnname'>peekable</a>(self) -> <a class="struct" href="../../std/iter/struct.Peekable.html" title="struct std::iter::Peekable">Peekable</a><Self></code></span></h3><div class='docblock'><p>Creates an iterator which can use <code>peek</code> to look at the next element of
the iterator without consuming it.</p>
<p>Adds a <a href="struct.Peekable.html#method.peek"><code>peek</code></a> method to an iterator. See its documentation for
more information.</p>
<p>Note that the underlying iterator is still advanced when <a href="struct.Peekable.html#method.peek"><code>peek</code></a> is
called for the first time: In order to retrieve the next element,
<a href="../../std/iter/trait.Iterator.html#tymethod.next"><code>next</code></a> is called on the underlying iterator, hence any side effects (i.e.
anything other than fetching the next value) of the <a href="../../std/iter/trait.Iterator.html#tymethod.next"><code>next</code></a> method
will occur.</p>
<h1 id='examples-12' class='section-header'><a href='#examples-12'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">xs</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">xs</span>.<span class="ident">iter</span>().<span class="ident">peekable</span>();
<span class="comment">// peek() lets us see into the future</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">peek</span>(), <span class="prelude-val">Some</span>(<span class="op">&&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="comment">// we can peek() multiple times, the iterator won't advance</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">peek</span>(), <span class="prelude-val">Some</span>(<span class="op">&&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">peek</span>(), <span class="prelude-val">Some</span>(<span class="op">&&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="comment">// after the iterator is finished, so is peek()</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">peek</span>(), <span class="prelude-val">None</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20xs%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20xs.iter().peekable()%3B%0A%0A%2F%2F%20peek()%20lets%20us%20see%20into%20the%20future%0Aassert_eq!(iter.peek()%2C%20Some(%26%261))%3B%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0A%0A%2F%2F%20we%20can%20peek()%20multiple%20times%2C%20the%20iterator%20won't%20advance%0Aassert_eq!(iter.peek()%2C%20Some(%26%263))%3B%0Aassert_eq!(iter.peek()%2C%20Some(%26%263))%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0A%0A%2F%2F%20after%20the%20iterator%20is%20finished%2C%20so%20is%20peek()%0Aassert_eq!(iter.peek()%2C%20None)%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.skip_while' class='method'><span id='skip_while.v' class='invisible'><code>fn <a href='#method.skip_while' class='fnname'>skip_while</a><P>(self, predicate: P) -> <a class="struct" href="../../std/iter/struct.SkipWhile.html" title="struct std::iter::SkipWhile">SkipWhile</a><Self, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></span></h3><div class='docblock'><p>Creates an iterator that <a href="#method.skip"><code>skip</code></a>s elements based on a predicate.</p>
<p><code>skip_while()</code> takes a closure as an argument. It will call this
closure on each element of the iterator, and ignore elements
until it returns <code>false</code>.</p>
<p>After <code>false</code> is returned, <code>skip_while()</code>'s job is over, and the
rest of the elements are yielded.</p>
<h1 id='examples-13' class='section-header'><a href='#examples-13'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">1i32</span>, <span class="number">0</span>, <span class="number">1</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">skip_while</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">is_negative</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">0</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-1i32%2C%200%2C%201%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().skip_while(%7Cx%7C%20x.is_negative())%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%260))%3B%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Because the closure passed to <code>skip_while()</code> takes a reference, and many
iterators iterate over references, this leads to a possibly confusing
situation, where the type of the closure is a double reference:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">1</span>, <span class="number">0</span>, <span class="number">1</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">skip_while</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">x</span> <span class="op"><</span> <span class="number">0</span>); <span class="comment">// need two *s!</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">0</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-1%2C%200%2C%201%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().skip_while(%7Cx%7C%20**x%20%3C%200)%3B%20%2F%2F%20need%20two%20*s!%0A%0Aassert_eq!(iter.next()%2C%20Some(%260))%3B%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Stopping after an initial <code>false</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">1</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="op">-</span><span class="number">2</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">skip_while</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">x</span> <span class="op"><</span> <span class="number">0</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">0</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="comment">// while this would have been false, since we already got a false,</span>
<span class="comment">// skip_while() isn't used any more</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="op">-</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-1%2C%200%2C%201%2C%20-2%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().skip_while(%7Cx%7C%20**x%20%3C%200)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%260))%3B%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0A%0A%2F%2F%20while%20this%20would%20have%20been%20false%2C%20since%20we%20already%20got%20a%20false%2C%0A%2F%2F%20skip_while()%20isn't%20used%20any%20more%0Aassert_eq!(iter.next()%2C%20Some(%26-2))%3B%0A%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.take_while' class='method'><span id='take_while.v' class='invisible'><code>fn <a href='#method.take_while' class='fnname'>take_while</a><P>(self, predicate: P) -> <a class="struct" href="../../std/iter/struct.TakeWhile.html" title="struct std::iter::TakeWhile">TakeWhile</a><Self, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></span></h3><div class='docblock'><p>Creates an iterator that yields elements based on a predicate.</p>
<p><code>take_while()</code> takes a closure as an argument. It will call this
closure on each element of the iterator, and yield elements
while it returns <code>true</code>.</p>
<p>After <code>false</code> is returned, <code>take_while()</code>'s job is over, and the
rest of the elements are ignored.</p>
<h1 id='examples-14' class='section-header'><a href='#examples-14'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">1i32</span>, <span class="number">0</span>, <span class="number">1</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">take_while</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">is_negative</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="op">-</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-1i32%2C%200%2C%201%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().take_while(%7Cx%7C%20x.is_negative())%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%26-1))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Because the closure passed to <code>take_while()</code> takes a reference, and many
iterators iterate over references, this leads to a possibly confusing
situation, where the type of the closure is a double reference:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">1</span>, <span class="number">0</span>, <span class="number">1</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">take_while</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">x</span> <span class="op"><</span> <span class="number">0</span>); <span class="comment">// need two *s!</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="op">-</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-1%2C%200%2C%201%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().take_while(%7Cx%7C%20**x%20%3C%200)%3B%20%2F%2F%20need%20two%20*s!%0A%0Aassert_eq!(iter.next()%2C%20Some(%26-1))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Stopping after an initial <code>false</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">1</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="op">-</span><span class="number">2</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>().<span class="ident">take_while</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">x</span> <span class="op"><</span> <span class="number">0</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="op">-</span><span class="number">1</span>));
<span class="comment">// We have more elements that are less than zero, but since we already</span>
<span class="comment">// got a false, take_while() isn't used any more</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-1%2C%200%2C%201%2C%20-2%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter().take_while(%7Cx%7C%20**x%20%3C%200)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%26-1))%3B%0A%0A%2F%2F%20We%20have%20more%20elements%20that%20are%20less%20than%20zero%2C%20but%20since%20we%20already%0A%2F%2F%20got%20a%20false%2C%20take_while()%20isn't%20used%20any%20more%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Because <code>take_while()</code> needs to look at the value in order to see if it
should be included or not, consuming iterators will see that it is
removed:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>();
<span class="kw">let</span> <span class="ident">result</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">by_ref</span>()
.<span class="ident">take_while</span>(<span class="op">|</span><span class="ident">n</span><span class="op">|</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">n</span> <span class="op">!=</span> <span class="number">3</span>)
.<span class="ident">cloned</span>()
.<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">2</span>]);
<span class="kw">let</span> <span class="ident">result</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="kw-2">&</span>[<span class="number">4</span>]);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%2C%204%5D%3B%0Alet%20mut%20iter%20%3D%20a.into_iter()%3B%0A%0Alet%20result%3A%20Vec%3Ci32%3E%20%3D%20iter.by_ref()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.take_while(%7Cn%7C%20**n%20!%3D%203)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.cloned()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.collect()%3B%0A%0Aassert_eq!(result%2C%20%26%5B1%2C%202%5D)%3B%0A%0Alet%20result%3A%20Vec%3Ci32%3E%20%3D%20iter.cloned().collect()%3B%0A%0Aassert_eq!(result%2C%20%26%5B4%5D)%3B%0A%7D">Run</a></pre>
<p>The <code>3</code> is no longer there, because it was consumed in order to see if
the iteration should stop, but wasn't placed back into the iterator or
some similar thing.</p>
</div><h3 id='method.skip' class='method'><span id='skip.v' class='invisible'><code>fn <a href='#method.skip' class='fnname'>skip</a>(self, n: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="struct" href="../../std/iter/struct.Skip.html" title="struct std::iter::Skip">Skip</a><Self></code></span></h3><div class='docblock'><p>Creates an iterator that skips the first <code>n</code> elements.</p>
<p>After they have been consumed, the rest of the elements are yielded.</p>
<h1 id='examples-15' class='section-header'><a href='#examples-15'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">skip</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter().skip(2)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.take' class='method'><span id='take.v' class='invisible'><code>fn <a href='#method.take' class='fnname'>take</a>(self, n: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="struct" href="../../std/iter/struct.Take.html" title="struct std::iter::Take">Take</a><Self></code></span></h3><div class='docblock'><p>Creates an iterator that yields its first <code>n</code> elements.</p>
<h1 id='examples-16' class='section-header'><a href='#examples-16'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">take</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter().take(2)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
<p><code>take()</code> is often used with an infinite iterator, to make it finite:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> (<span class="number">0</span>..).<span class="ident">take</span>(<span class="number">3</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">0</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20mut%20iter%20%3D%20(0..).take(3)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(0))%3B%0Aassert_eq!(iter.next()%2C%20Some(1))%3B%0Aassert_eq!(iter.next()%2C%20Some(2))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.scan' class='method'><span id='scan.v' class='invisible'><code>fn <a href='#method.scan' class='fnname'>scan</a><St, B, F>(self, initial_state: St, f: F) -> <a class="struct" href="../../std/iter/struct.Scan.html" title="struct std::iter::Scan">Scan</a><Self, St, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&mut St, Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><B>, </span></code></span></h3><div class='docblock'><p>An iterator adaptor similar to <a href="#method.fold"><code>fold</code></a> that holds internal state and
produces a new iterator.</p>
<p><code>scan()</code> takes two arguments: an initial value which seeds the internal
state, and a closure with two arguments, the first being a mutable
reference to the internal state and the second an iterator element.
The closure can assign to the internal state to share state between
iterations.</p>
<p>On iteration, the closure will be applied to each element of the
iterator and the return value from the closure, an <a href="../../std/option/enum.Option.html"><code>Option</code></a>, is
yielded by the iterator.</p>
<h1 id='examples-17' class='section-header'><a href='#examples-17'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">scan</span>(<span class="number">1</span>, <span class="op">|</span><span class="ident">state</span>, <span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> {
<span class="comment">// each iteration, we'll multiply the state by the element</span>
<span class="kw-2">*</span><span class="ident">state</span> <span class="op">=</span> <span class="kw-2">*</span><span class="ident">state</span> <span class="op">*</span> <span class="ident">x</span>;
<span class="comment">// the value passed on to the next iteration</span>
<span class="prelude-val">Some</span>(<span class="kw-2">*</span><span class="ident">state</span>)
});
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">6</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter().scan(1%2C%20%7Cstate%2C%20%26x%7C%20%7B%0A%20%20%20%20%2F%2F%20each%20iteration%2C%20we'll%20multiply%20the%20state%20by%20the%20element%0A%20%20%20%20*state%20%3D%20*state%20*%20x%3B%0A%0A%20%20%20%20%2F%2F%20the%20value%20passed%20on%20to%20the%20next%20iteration%0A%20%20%20%20Some(*state)%0A%7D)%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(1))%3B%0Aassert_eq!(iter.next()%2C%20Some(2))%3B%0Aassert_eq!(iter.next()%2C%20Some(6))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.flat_map' class='method'><span id='flat_map.v' class='invisible'><code>fn <a href='#method.flat_map' class='fnname'>flat_map</a><U, F>(self, f: F) -> <a class="struct" href="../../std/iter/struct.FlatMap.html" title="struct std::iter::FlatMap">FlatMap</a><Self, U, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> U,<br> U: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>, </span></code></span></h3><div class='docblock'><p>Creates an iterator that works like map, but flattens nested structure.</p>
<p>The <a href="#method.map"><code>map</code></a> adapter is very useful, but only when the closure
argument produces values. If it produces an iterator instead, there's
an extra layer of indirection. <code>flat_map()</code> will remove this extra layer
on its own.</p>
<p>Another way of thinking about <code>flat_map()</code>: <a href="#method.map"><code>map</code></a>'s closure returns
one item for each element, and <code>flat_map()</code>'s closure returns an
iterator for each element.</p>
<h1 id='examples-18' class='section-header'><a href='#examples-18'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">words</span> <span class="op">=</span> [<span class="string">"alpha"</span>, <span class="string">"beta"</span>, <span class="string">"gamma"</span>];
<span class="comment">// chars() returns an iterator</span>
<span class="kw">let</span> <span class="ident">merged</span>: <span class="ident">String</span> <span class="op">=</span> <span class="ident">words</span>.<span class="ident">iter</span>()
.<span class="ident">flat_map</span>(<span class="op">|</span><span class="ident">s</span><span class="op">|</span> <span class="ident">s</span>.<span class="ident">chars</span>())
.<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">merged</span>, <span class="string">"alphabetagamma"</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20words%20%3D%20%5B%22alpha%22%2C%20%22beta%22%2C%20%22gamma%22%5D%3B%0A%0A%2F%2F%20chars()%20returns%20an%20iterator%0Alet%20merged%3A%20String%20%3D%20words.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.flat_map(%7Cs%7C%20s.chars())%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.collect()%3B%0Aassert_eq!(merged%2C%20%22alphabetagamma%22)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.fuse' class='method'><span id='fuse.v' class='invisible'><code>fn <a href='#method.fuse' class='fnname'>fuse</a>(self) -> <a class="struct" href="../../std/iter/struct.Fuse.html" title="struct std::iter::Fuse">Fuse</a><Self></code></span></h3><div class='docblock'><p>Creates an iterator which ends after the first <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>.</p>
<p>After an iterator returns <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>, future calls may or may not yield
<a href="../../std/option/enum.Option.html#variant.Some"><code>Some(T)</code></a> again. <code>fuse()</code> adapts an iterator, ensuring that after a
<a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is given, it will always return <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> forever.</p>
<h1 id='examples-19' class='section-header'><a href='#examples-19'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="comment">// an iterator which alternates between Some and None</span>
<span class="kw">struct</span> <span class="ident">Alternate</span> {
<span class="ident">state</span>: <span class="ident">i32</span>,
}
<span class="kw">impl</span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Alternate</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">i32</span>;
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">val</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">state</span>;
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">state</span> <span class="op">+</span> <span class="number">1</span>;
<span class="comment">// if it's even, Some(i32), else None</span>
<span class="kw">if</span> <span class="ident">val</span> <span class="op">%</span> <span class="number">2</span> <span class="op">==</span> <span class="number">0</span> {
<span class="prelude-val">Some</span>(<span class="ident">val</span>)
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">Alternate</span> { <span class="ident">state</span>: <span class="number">0</span> };
<span class="comment">// we can see our iterator going back and forth</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">0</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);
<span class="comment">// however, once we fuse it...</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">fuse</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="number">4</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);
<span class="comment">// it will always return None after the first time.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0A%2F%2F%20an%20iterator%20which%20alternates%20between%20Some%20and%20None%0Astruct%20Alternate%20%7B%0A%20%20%20%20state%3A%20i32%2C%0A%7D%0A%0Aimpl%20Iterator%20for%20Alternate%20%7B%0A%20%20%20%20type%20Item%20%3D%20i32%3B%0A%0A%20%20%20%20fn%20next(%26mut%20self)%20-%3E%20Option%3Ci32%3E%20%7B%0A%20%20%20%20%20%20%20%20let%20val%20%3D%20self.state%3B%0A%20%20%20%20%20%20%20%20self.state%20%3D%20self.state%20%2B%201%3B%0A%0A%20%20%20%20%20%20%20%20%2F%2F%20if%20it's%20even%2C%20Some(i32)%2C%20else%20None%0A%20%20%20%20%20%20%20%20if%20val%20%25%202%20%3D%3D%200%20%7B%0A%20%20%20%20%20%20%20%20%20%20%20%20Some(val)%0A%20%20%20%20%20%20%20%20%7D%20else%20%7B%0A%20%20%20%20%20%20%20%20%20%20%20%20None%0A%20%20%20%20%20%20%20%20%7D%0A%20%20%20%20%7D%0A%7D%0A%0Alet%20mut%20iter%20%3D%20Alternate%20%7B%20state%3A%200%20%7D%3B%0A%0A%2F%2F%20we%20can%20see%20our%20iterator%20going%20back%20and%20forth%0Aassert_eq!(iter.next()%2C%20Some(0))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0Aassert_eq!(iter.next()%2C%20Some(2))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%0A%2F%2F%20however%2C%20once%20we%20fuse%20it...%0Alet%20mut%20iter%20%3D%20iter.fuse()%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(4))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%0A%2F%2F%20it%20will%20always%20return%20None%20after%20the%20first%20time.%0Aassert_eq!(iter.next()%2C%20None)%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.inspect' class='method'><span id='inspect.v' class='invisible'><code>fn <a href='#method.inspect' class='fnname'>inspect</a><F>(self, f: F) -> <a class="struct" href="../../std/iter/struct.Inspect.html" title="struct std::iter::Inspect">Inspect</a><Self, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.tuple.html">()</a>, </span></code></span></h3><div class='docblock'><p>Do something with each element of an iterator, passing the value on.</p>
<p>When using iterators, you'll often chain several of them together.
While working on such code, you might want to check out what's
happening at various parts in the pipeline. To do that, insert
a call to <code>inspect()</code>.</p>
<p>It's much more common for <code>inspect()</code> to be used as a debugging tool
than to exist in your final code, but never say never.</p>
<h1 id='examples-20' class='section-header'><a href='#examples-20'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">4</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="comment">// this iterator sequence is complex.</span>
<span class="kw">let</span> <span class="ident">sum</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>()
.<span class="ident">cloned</span>()
.<span class="ident">filter</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">%</span> <span class="number">2</span> <span class="op">==</span> <span class="number">0</span>)
.<span class="ident">fold</span>(<span class="number">0</span>, <span class="op">|</span><span class="ident">sum</span>, <span class="ident">i</span><span class="op">|</span> <span class="ident">sum</span> <span class="op">+</span> <span class="ident">i</span>);
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">sum</span>);
<span class="comment">// let's add some inspect() calls to investigate what's happening</span>
<span class="kw">let</span> <span class="ident">sum</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>()
.<span class="ident">cloned</span>()
.<span class="ident">inspect</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="macro">println</span><span class="macro">!</span>(<span class="string">"about to filter: {}"</span>, <span class="ident">x</span>))
.<span class="ident">filter</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">%</span> <span class="number">2</span> <span class="op">==</span> <span class="number">0</span>)
.<span class="ident">inspect</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="macro">println</span><span class="macro">!</span>(<span class="string">"made it through filter: {}"</span>, <span class="ident">x</span>))
.<span class="ident">fold</span>(<span class="number">0</span>, <span class="op">|</span><span class="ident">sum</span>, <span class="ident">i</span><span class="op">|</span> <span class="ident">sum</span> <span class="op">+</span> <span class="ident">i</span>);
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">sum</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%204%2C%202%2C%203%5D%3B%0A%0A%2F%2F%20this%20iterator%20sequence%20is%20complex.%0Alet%20sum%20%3D%20a.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20.cloned()%0A%20%20%20%20%20%20%20%20%20%20%20%20.filter(%7C%26x%7C%20x%20%25%202%20%3D%3D%200)%0A%20%20%20%20%20%20%20%20%20%20%20%20.fold(0%2C%20%7Csum%2C%20i%7C%20sum%20%2B%20i)%3B%0A%0Aprintln!(%22%7B%7D%22%2C%20sum)%3B%0A%0A%2F%2F%20let's%20add%20some%20inspect()%20calls%20to%20investigate%20what's%20happening%0Alet%20sum%20%3D%20a.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20.cloned()%0A%20%20%20%20%20%20%20%20%20%20%20%20.inspect(%7Cx%7C%20println!(%22about%20to%20filter%3A%20%7B%7D%22%2C%20x))%0A%20%20%20%20%20%20%20%20%20%20%20%20.filter(%7C%26x%7C%20x%20%25%202%20%3D%3D%200)%0A%20%20%20%20%20%20%20%20%20%20%20%20.inspect(%7Cx%7C%20println!(%22made%20it%20through%20filter%3A%20%7B%7D%22%2C%20x))%0A%20%20%20%20%20%20%20%20%20%20%20%20.fold(0%2C%20%7Csum%2C%20i%7C%20sum%20%2B%20i)%3B%0A%0Aprintln!(%22%7B%7D%22%2C%20sum)%3B%0A%7D">Run</a></pre>
<p>This will print:</p>
<pre><code class="language-text">about to filter: 1
about to filter: 4
made it through filter: 4
about to filter: 2
made it through filter: 2
about to filter: 3
6
</code></pre>
</div><h3 id='method.by_ref' class='method'><span id='by_ref.v' class='invisible'><code>fn <a href='#method.by_ref' class='fnname'>by_ref</a>(&mut self) -> &mut Self</code></span></h3><div class='docblock'><p>Borrows an iterator, rather than consuming it.</p>
<p>This is useful to allow applying iterator adaptors while still
retaining ownership of the original iterator.</p>
<h1 id='examples-21' class='section-header'><a href='#examples-21'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>();
<span class="kw">let</span> <span class="ident">sum</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">take</span>(<span class="number">5</span>)
.<span class="ident">fold</span>(<span class="number">0</span>, <span class="op">|</span><span class="ident">acc</span>, <span class="kw-2">&</span><span class="ident">i</span><span class="op">|</span> <span class="ident">acc</span> <span class="op">+</span> <span class="ident">i</span> );
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">sum</span>, <span class="number">6</span>);
<span class="comment">// if we try to use iter again, it won't work. The following line</span>
<span class="comment">// gives "error: use of moved value: `iter`</span>
<span class="comment">// assert_eq!(iter.next(), None);</span>
<span class="comment">// let's try that again</span>
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>();
<span class="comment">// instead, we add in a .by_ref()</span>
<span class="kw">let</span> <span class="ident">sum</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="ident">iter</span>.<span class="ident">by_ref</span>()
.<span class="ident">take</span>(<span class="number">2</span>)
.<span class="ident">fold</span>(<span class="number">0</span>, <span class="op">|</span><span class="ident">acc</span>, <span class="kw-2">&</span><span class="ident">i</span><span class="op">|</span> <span class="ident">acc</span> <span class="op">+</span> <span class="ident">i</span> );
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">sum</span>, <span class="number">3</span>);
<span class="comment">// now this is just fine:</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20iter%20%3D%20a.into_iter()%3B%0A%0Alet%20sum%3A%20i32%20%3D%20iter.take(5)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.fold(0%2C%20%7Cacc%2C%20%26i%7C%20acc%20%2B%20i%20)%3B%0A%0Aassert_eq!(sum%2C%206)%3B%0A%0A%2F%2F%20if%20we%20try%20to%20use%20iter%20again%2C%20it%20won't%20work.%20The%20following%20line%0A%2F%2F%20gives%20%22error%3A%20use%20of%20moved%20value%3A%20%60iter%60%0A%2F%2F%20assert_eq!(iter.next()%2C%20None)%3B%0A%0A%2F%2F%20let's%20try%20that%20again%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.into_iter()%3B%0A%0A%2F%2F%20instead%2C%20we%20add%20in%20a%20.by_ref()%0Alet%20sum%3A%20i32%20%3D%20iter.by_ref()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.take(2)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.fold(0%2C%20%7Cacc%2C%20%26i%7C%20acc%20%2B%20i%20)%3B%0A%0Aassert_eq!(sum%2C%203)%3B%0A%0A%2F%2F%20now%20this%20is%20just%20fine%3A%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.collect' class='method'><span id='collect.v' class='invisible'><code>fn <a href='#method.collect' class='fnname'>collect</a><B>(self) -> B <span class="where fmt-newline">where<br> B: <a class="trait" href="../../std/iter/trait.FromIterator.html" title="trait std::iter::FromIterator">FromIterator</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>, </span></code></span></h3><div class='docblock'><p>Transforms an iterator into a collection.</p>
<p><code>collect()</code> can take anything iterable, and turn it into a relevant
collection. This is one of the more powerful methods in the standard
library, used in a variety of contexts.</p>
<p>The most basic pattern in which <code>collect()</code> is used is to turn one
collection into another. You take a collection, call <a href="../../std/iter/trait.Iterator.html#tymethod.next"><code>iter</code></a> on it,
do a bunch of transformations, and then <code>collect()</code> at the end.</p>
<p>One of the keys to <code>collect()</code>'s power is that many things you might
not think of as 'collections' actually are. For example, a <a href="../../std/string/struct.String.html"><code>String</code></a>
is a collection of <a href="../../std/primitive.char.html"><code>char</code></a>s. And a collection of
<a href="../../std/result/enum.Result.html"><code>Result<T, E></code></a> can be thought of as single
<a href="../../std/result/enum.Result.html"><code>Result</code></a><code><Collection<T>, E></code>. See the examples below for more.</p>
<p>Because <code>collect()</code> is so general, it can cause problems with type
inference. As such, <code>collect()</code> is one of the few times you'll see
the syntax affectionately known as the 'turbofish': <code>::<></code>. This
helps the inference algorithm understand specifically which collection
you're trying to collect into.</p>
<h1 id='examples-22' class='section-header'><a href='#examples-22'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">doubled</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>()
.<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">*</span> <span class="number">2</span>)
.<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="macro">vec</span><span class="macro">!</span>[<span class="number">2</span>, <span class="number">4</span>, <span class="number">6</span>], <span class="ident">doubled</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20doubled%3A%20Vec%3Ci32%3E%20%3D%20a.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.map(%7C%26x%7C%20x%20*%202)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.collect()%3B%0A%0Aassert_eq!(vec!%5B2%2C%204%2C%206%5D%2C%20doubled)%3B%0A%7D">Run</a></pre>
<p>Note that we needed the <code>: Vec<i32></code> on the left-hand side. This is because
we could collect into, for example, a <a href="../../std/collections/struct.VecDeque.html"><code>VecDeque<T></code></a> instead:</p>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">VecDeque</span>;
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">doubled</span>: <span class="ident">VecDeque</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>()
.<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">*</span> <span class="number">2</span>)
.<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">2</span>, <span class="ident">doubled</span>[<span class="number">0</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">4</span>, <span class="ident">doubled</span>[<span class="number">1</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">6</span>, <span class="ident">doubled</span>[<span class="number">2</span>]);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AVecDeque%3B%0A%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20doubled%3A%20VecDeque%3Ci32%3E%20%3D%20a.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.map(%7C%26x%7C%20x%20*%202)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.collect()%3B%0A%0Aassert_eq!(2%2C%20doubled%5B0%5D)%3B%0Aassert_eq!(4%2C%20doubled%5B1%5D)%3B%0Aassert_eq!(6%2C%20doubled%5B2%5D)%3B%0A%7D">Run</a></pre>
<p>Using the 'turbofish' instead of annotating <code>doubled</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">doubled</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>()
.<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">*</span> <span class="number">2</span>)
.<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">i32</span><span class="op">>></span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="macro">vec</span><span class="macro">!</span>[<span class="number">2</span>, <span class="number">4</span>, <span class="number">6</span>], <span class="ident">doubled</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20doubled%20%3D%20a.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.map(%7C%26x%7C%20x%20*%202)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.collect%3A%3A%3CVec%3Ci32%3E%3E()%3B%0A%0Aassert_eq!(vec!%5B2%2C%204%2C%206%5D%2C%20doubled)%3B%0A%7D">Run</a></pre>
<p>Because <code>collect()</code> cares about what you're collecting into, you can
still use a partial type hint, <code>_</code>, with the turbofish:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">doubled</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>()
.<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">*</span> <span class="number">2</span>)
.<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span>_<span class="op">>></span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="macro">vec</span><span class="macro">!</span>[<span class="number">2</span>, <span class="number">4</span>, <span class="number">6</span>], <span class="ident">doubled</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20doubled%20%3D%20a.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.map(%7C%26x%7C%20x%20*%202)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.collect%3A%3A%3CVec%3C_%3E%3E()%3B%0A%0Aassert_eq!(vec!%5B2%2C%204%2C%206%5D%2C%20doubled)%3B%0A%7D">Run</a></pre>
<p>Using <code>collect()</code> to make a <a href="../../std/string/struct.String.html"><code>String</code></a>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">chars</span> <span class="op">=</span> [<span class="string">'g'</span>, <span class="string">'d'</span>, <span class="string">'k'</span>, <span class="string">'k'</span>, <span class="string">'n'</span>];
<span class="kw">let</span> <span class="ident">hello</span>: <span class="ident">String</span> <span class="op">=</span> <span class="ident">chars</span>.<span class="ident">iter</span>()
.<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="kw">as</span> <span class="ident">u8</span>)
.<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> (<span class="ident">x</span> <span class="op">+</span> <span class="number">1</span>) <span class="kw">as</span> <span class="ident">char</span>)
.<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">"hello"</span>, <span class="ident">hello</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20chars%20%3D%20%5B'g'%2C%20'd'%2C%20'k'%2C%20'k'%2C%20'n'%5D%3B%0A%0Alet%20hello%3A%20String%20%3D%20chars.iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.map(%7C%26x%7C%20x%20as%20u8)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.map(%7Cx%7C%20(x%20%2B%201)%20as%20char)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.collect()%3B%0A%0Aassert_eq!(%22hello%22%2C%20hello)%3B%0A%7D">Run</a></pre>
<p>If you have a list of <a href="../../std/result/enum.Result.html"><code>Result<T, E></code></a>s, you can use <code>collect()</code> to
see if any of them failed:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">results</span> <span class="op">=</span> [<span class="prelude-val">Ok</span>(<span class="number">1</span>), <span class="prelude-val">Err</span>(<span class="string">"nope"</span>), <span class="prelude-val">Ok</span>(<span class="number">3</span>), <span class="prelude-val">Err</span>(<span class="string">"bad"</span>)];
<span class="kw">let</span> <span class="ident">result</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span>_<span class="op">></span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">results</span>.<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="comment">// gives us the first error</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Err</span>(<span class="string">"nope"</span>), <span class="ident">result</span>);
<span class="kw">let</span> <span class="ident">results</span> <span class="op">=</span> [<span class="prelude-val">Ok</span>(<span class="number">1</span>), <span class="prelude-val">Ok</span>(<span class="number">3</span>)];
<span class="kw">let</span> <span class="ident">result</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span>_<span class="op">></span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">results</span>.<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="comment">// gives us the list of answers</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Ok</span>(<span class="macro">vec</span><span class="macro">!</span>[<span class="number">1</span>, <span class="number">3</span>]), <span class="ident">result</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20results%20%3D%20%5BOk(1)%2C%20Err(%22nope%22)%2C%20Ok(3)%2C%20Err(%22bad%22)%5D%3B%0A%0Alet%20result%3A%20Result%3CVec%3C_%3E%2C%20%26str%3E%20%3D%20results.iter().cloned().collect()%3B%0A%0A%2F%2F%20gives%20us%20the%20first%20error%0Aassert_eq!(Err(%22nope%22)%2C%20result)%3B%0A%0Alet%20results%20%3D%20%5BOk(1)%2C%20Ok(3)%5D%3B%0A%0Alet%20result%3A%20Result%3CVec%3C_%3E%2C%20%26str%3E%20%3D%20results.iter().cloned().collect()%3B%0A%0A%2F%2F%20gives%20us%20the%20list%20of%20answers%0Aassert_eq!(Ok(vec!%5B1%2C%203%5D)%2C%20result)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.partition' class='method'><span id='partition.v' class='invisible'><code>fn <a href='#method.partition' class='fnname'>partition</a><B, F>(self, f: F) -> <a class="primitive" href="../primitive.tuple.html">(</a>B, B<a class="primitive" href="../primitive.tuple.html">)</a> <span class="where fmt-newline">where<br> B: <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a> + <a class="trait" href="../../std/iter/trait.Extend.html" title="trait std::iter::Extend">Extend</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>,<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></span></h3><div class='docblock'><p>Consumes an iterator, creating two collections from it.</p>
<p>The predicate passed to <code>partition()</code> can return <code>true</code>, or <code>false</code>.
<code>partition()</code> returns a pair, all of the elements for which it returned
<code>true</code>, and all of the elements for which it returned <code>false</code>.</p>
<h1 id='examples-23' class='section-header'><a href='#examples-23'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> (<span class="ident">even</span>, <span class="ident">odd</span>): (<span class="ident">Vec</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span>, <span class="ident">Vec</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span>) <span class="op">=</span> <span class="ident">a</span>.<span class="ident">into_iter</span>()
.<span class="ident">partition</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">n</span><span class="op">|</span> <span class="ident">n</span> <span class="op">%</span> <span class="number">2</span> <span class="op">==</span> <span class="number">0</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">even</span>, <span class="macro">vec</span><span class="macro">!</span>[<span class="number">2</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">odd</span>, <span class="macro">vec</span><span class="macro">!</span>[<span class="number">1</span>, <span class="number">3</span>]);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20(even%2C%20odd)%3A%20(Vec%3Ci32%3E%2C%20Vec%3Ci32%3E)%20%3D%20a.into_iter()%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.partition(%7C%26n%7C%20n%20%25%202%20%3D%3D%200)%3B%0A%0Aassert_eq!(even%2C%20vec!%5B2%5D)%3B%0Aassert_eq!(odd%2C%20vec!%5B1%2C%203%5D)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.fold' class='method'><span id='fold.v' class='invisible'><code>fn <a href='#method.fold' class='fnname'>fold</a><B, F>(self, init: B, f: F) -> B <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(B, Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B, </span></code></span></h3><div class='docblock'><p>An iterator adaptor that applies a function, producing a single, final value.</p>
<p><code>fold()</code> takes two arguments: an initial value, and a closure with two
arguments: an 'accumulator', and an element. The closure returns the value that
the accumulator should have for the next iteration.</p>
<p>The initial value is the value the accumulator will have on the first
call.</p>
<p>After applying this closure to every element of the iterator, <code>fold()</code>
returns the accumulator.</p>
<p>This operation is sometimes called 'reduce' or 'inject'.</p>
<p>Folding is useful whenever you have a collection of something, and want
to produce a single value from it.</p>
<h1 id='examples-24' class='section-header'><a href='#examples-24'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="comment">// the sum of all of the elements of a</span>
<span class="kw">let</span> <span class="ident">sum</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>()
.<span class="ident">fold</span>(<span class="number">0</span>, <span class="op">|</span><span class="ident">acc</span>, <span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">acc</span> <span class="op">+</span> <span class="ident">x</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">sum</span>, <span class="number">6</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0A%2F%2F%20the%20sum%20of%20all%20of%20the%20elements%20of%20a%0Alet%20sum%20%3D%20a.iter()%0A%20%20%20%20%20%20%20%20%20%20%20.fold(0%2C%20%7Cacc%2C%20%26x%7C%20acc%20%2B%20x)%3B%0A%0Aassert_eq!(sum%2C%206)%3B%0A%7D">Run</a></pre>
<p>Let's walk through each step of the iteration here:</p>
<table>
<thead>
<tr>
<th>element</th>
<th>acc</th>
<th>x</th>
<th>result</th>
</tr>
</thead>
<tbody>
<tr>
<td></td>
<td>0</td>
<td></td>
<td></td>
</tr>
<tr>
<td>1</td>
<td>0</td>
<td>1</td>
<td>1</td>
</tr>
<tr>
<td>2</td>
<td>1</td>
<td>2</td>
<td>3</td>
</tr>
<tr>
<td>3</td>
<td>3</td>
<td>3</td>
<td>6</td>
</tr>
</tbody>
</table>
<p>And so, our final result, <code>6</code>.</p>
<p>It's common for people who haven't used iterators a lot to
use a <code>for</code> loop with a list of things to build up a result. Those
can be turned into <code>fold()</code>s:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">numbers</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">result</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// for loop:</span>
<span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">numbers</span> {
<span class="ident">result</span> <span class="op">=</span> <span class="ident">result</span> <span class="op">+</span> <span class="ident">i</span>;
}
<span class="comment">// fold:</span>
<span class="kw">let</span> <span class="ident">result2</span> <span class="op">=</span> <span class="ident">numbers</span>.<span class="ident">iter</span>().<span class="ident">fold</span>(<span class="number">0</span>, <span class="op">|</span><span class="ident">acc</span>, <span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">acc</span> <span class="op">+</span> <span class="ident">x</span>);
<span class="comment">// they're the same</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">result</span>, <span class="ident">result2</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20numbers%20%3D%20%5B1%2C%202%2C%203%2C%204%2C%205%5D%3B%0A%0Alet%20mut%20result%20%3D%200%3B%0A%0A%2F%2F%20for%20loop%3A%0Afor%20i%20in%20%26numbers%20%7B%0A%20%20%20%20result%20%3D%20result%20%2B%20i%3B%0A%7D%0A%0A%2F%2F%20fold%3A%0Alet%20result2%20%3D%20numbers.iter().fold(0%2C%20%7Cacc%2C%20%26x%7C%20acc%20%2B%20x)%3B%0A%0A%2F%2F%20they're%20the%20same%0Aassert_eq!(result%2C%20result2)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.all' class='method'><span id='all.v' class='invisible'><code>fn <a href='#method.all' class='fnname'>all</a><F>(&mut self, f: F) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></span></h3><div class='docblock'><p>Tests if every element of the iterator matches a predicate.</p>
<p><code>all()</code> takes a closure that returns <code>true</code> or <code>false</code>. It applies
this closure to each element of the iterator, and if they all return
<code>true</code>, then so does <code>all()</code>. If any of them return <code>false</code>, it
returns <code>false</code>.</p>
<p><code>all()</code> is short-circuiting; in other words, it will stop processing
as soon as it finds a <code>false</code>, given that no matter what else happens,
the result will also be <code>false</code>.</p>
<p>An empty iterator returns <code>true</code>.</p>
<h1 id='examples-25' class='section-header'><a href='#examples-25'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">all</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">></span> <span class="number">0</span>));
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">all</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">></span> <span class="number">2</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Aassert!(a.iter().all(%7C%26x%7C%20x%20%3E%200))%3B%0A%0Aassert!(!a.iter().all(%7C%26x%7C%20x%20%3E%202))%3B%0A%7D">Run</a></pre>
<p>Stopping at the first <code>false</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">iter</span>.<span class="ident">all</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">!=</span> <span class="number">2</span>));
<span class="comment">// we can still use `iter`, as there are more elements.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter()%3B%0A%0Aassert!(!iter.all(%7C%26x%7C%20x%20!%3D%202))%3B%0A%0A%2F%2F%20we%20can%20still%20use%20%60iter%60%2C%20as%20there%20are%20more%20elements.%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0A%7D">Run</a></pre>
</div><h3 id='method.any' class='method'><span id='any.v' class='invisible'><code>fn <a href='#method.any' class='fnname'>any</a><F>(&mut self, f: F) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></span></h3><div class='docblock'><p>Tests if any element of the iterator matches a predicate.</p>
<p><code>any()</code> takes a closure that returns <code>true</code> or <code>false</code>. It applies
this closure to each element of the iterator, and if any of them return
<code>true</code>, then so does <code>any()</code>. If they all return <code>false</code>, it
returns <code>false</code>.</p>
<p><code>any()</code> is short-circuiting; in other words, it will stop processing
as soon as it finds a <code>true</code>, given that no matter what else happens,
the result will also be <code>true</code>.</p>
<p>An empty iterator returns <code>false</code>.</p>
<h1 id='examples-26' class='section-header'><a href='#examples-26'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">any</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">></span> <span class="number">0</span>));
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">any</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">></span> <span class="number">5</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Aassert!(a.iter().any(%7C%26x%7C%20x%20%3E%200))%3B%0A%0Aassert!(!a.iter().any(%7C%26x%7C%20x%20%3E%205))%3B%0A%7D">Run</a></pre>
<p>Stopping at the first <code>true</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">any</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">!=</span> <span class="number">2</span>));
<span class="comment">// we can still use `iter`, as there are more elements.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter()%3B%0A%0Aassert!(iter.any(%7C%26x%7C%20x%20!%3D%202))%3B%0A%0A%2F%2F%20we%20can%20still%20use%20%60iter%60%2C%20as%20there%20are%20more%20elements.%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0A%7D">Run</a></pre>
</div><h3 id='method.find' class='method'><span id='find.v' class='invisible'><code>fn <a href='#method.find' class='fnname'>find</a><P>(&mut self, predicate: P) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></span></h3><div class='docblock'><p>Searches for an element of an iterator that satisfies a predicate.</p>
<p><code>find()</code> takes a closure that returns <code>true</code> or <code>false</code>. It applies
this closure to each element of the iterator, and if any of them return
<code>true</code>, then <code>find()</code> returns <a href="../../std/option/enum.Option.html#variant.Some"><code>Some(element)</code></a>. If they all return
<code>false</code>, it returns <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>.</p>
<p><code>find()</code> is short-circuiting; in other words, it will stop processing
as soon as the closure returns <code>true</code>.</p>
<p>Because <code>find()</code> takes a reference, and many iterators iterate over
references, this leads to a possibly confusing situation where the
argument is a double reference. You can see this effect in the
examples below, with <code>&&x</code>.</p>
<h1 id='examples-27' class='section-header'><a href='#examples-27'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">find</span>(<span class="op">|</span><span class="op">&&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">2</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">find</span>(<span class="op">|</span><span class="op">&&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">5</span>), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Aassert_eq!(a.iter().find(%7C%26%26x%7C%20x%20%3D%3D%202)%2C%20Some(%262))%3B%0A%0Aassert_eq!(a.iter().find(%7C%26%26x%7C%20x%20%3D%3D%205)%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Stopping at the first <code>true</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">find</span>(<span class="op">|</span><span class="op">&&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">2</span>), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="comment">// we can still use `iter`, as there are more elements.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter()%3B%0A%0Aassert_eq!(iter.find(%7C%26%26x%7C%20x%20%3D%3D%202)%2C%20Some(%262))%3B%0A%0A%2F%2F%20we%20can%20still%20use%20%60iter%60%2C%20as%20there%20are%20more%20elements.%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0A%7D">Run</a></pre>
</div><h3 id='method.position' class='method'><span id='position.v' class='invisible'><code>fn <a href='#method.position' class='fnname'>position</a><P>(&mut self, predicate: P) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.usize.html">usize</a>> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></span></h3><div class='docblock'><p>Searches for an element in an iterator, returning its index.</p>
<p><code>position()</code> takes a closure that returns <code>true</code> or <code>false</code>. It applies
this closure to each element of the iterator, and if one of them
returns <code>true</code>, then <code>position()</code> returns <a href="../../std/option/enum.Option.html#variant.Some"><code>Some(index)</code></a>. If all of
them return <code>false</code>, it returns <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>.</p>
<p><code>position()</code> is short-circuiting; in other words, it will stop
processing as soon as it finds a <code>true</code>.</p>
<h1 id='overflow-behavior-2' class='section-header'><a href='#overflow-behavior-2'>Overflow Behavior</a></h1>
<p>The method does no guarding against overflows, so if there are more
than <a href="../../std/usize/constant.MAX.html"><code>usize::MAX</code></a> non-matching elements, it either produces the wrong
result or panics. If debug assertions are enabled, a panic is
guaranteed.</p>
<h1 id='panics-3' class='section-header'><a href='#panics-3'>Panics</a></h1>
<p>This function might panic if the iterator has more than <code>usize::MAX</code>
non-matching elements.</p>
<h1 id='examples-28' class='section-header'><a href='#examples-28'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">position</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">2</span>), <span class="prelude-val">Some</span>(<span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">position</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">5</span>), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Aassert_eq!(a.iter().position(%7C%26x%7C%20x%20%3D%3D%202)%2C%20Some(1))%3B%0A%0Aassert_eq!(a.iter().position(%7C%26x%7C%20x%20%3D%3D%205)%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Stopping at the first <code>true</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">position</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">>=</span> <span class="number">2</span>), <span class="prelude-val">Some</span>(<span class="number">1</span>));
<span class="comment">// we can still use `iter`, as there are more elements.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="comment">// The returned index depends on iterator state</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">position</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">4</span>), <span class="prelude-val">Some</span>(<span class="number">0</span>));
<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%2C%204%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter()%3B%0A%0Aassert_eq!(iter.position(%7C%26x%7C%20x%20%3E%3D%202)%2C%20Some(1))%3B%0A%0A%2F%2F%20we%20can%20still%20use%20%60iter%60%2C%20as%20there%20are%20more%20elements.%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0A%0A%2F%2F%20The%20returned%20index%20depends%20on%20iterator%20state%0Aassert_eq!(iter.position(%7C%26x%7C%20x%20%3D%3D%204)%2C%20Some(0))%3B%0A%7D">Run</a></pre>
</div><h3 id='method.rposition' class='method'><span id='rposition.v' class='invisible'><code>fn <a href='#method.rposition' class='fnname'>rposition</a><P>(&mut self, predicate: P) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.usize.html">usize</a>> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>,<br> Self: <a class="trait" href="../../std/iter/trait.ExactSizeIterator.html" title="trait std::iter::ExactSizeIterator">ExactSizeIterator</a> + <a class="trait" href="../../std/iter/trait.DoubleEndedIterator.html" title="trait std::iter::DoubleEndedIterator">DoubleEndedIterator</a>, </span></code></span></h3><div class='docblock'><p>Searches for an element in an iterator from the right, returning its
index.</p>
<p><code>rposition()</code> takes a closure that returns <code>true</code> or <code>false</code>. It applies
this closure to each element of the iterator, starting from the end,
and if one of them returns <code>true</code>, then <code>rposition()</code> returns
<a href="../../std/option/enum.Option.html#variant.Some"><code>Some(index)</code></a>. If all of them return <code>false</code>, it returns <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>.</p>
<p><code>rposition()</code> is short-circuiting; in other words, it will stop
processing as soon as it finds a <code>true</code>.</p>
<h1 id='examples-29' class='section-header'><a href='#examples-29'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">rposition</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">3</span>), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">rposition</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">5</span>), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Aassert_eq!(a.iter().rposition(%7C%26x%7C%20x%20%3D%3D%203)%2C%20Some(2))%3B%0A%0Aassert_eq!(a.iter().rposition(%7C%26x%7C%20x%20%3D%3D%205)%2C%20None)%3B%0A%7D">Run</a></pre>
<p>Stopping at the first <code>true</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">rposition</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">2</span>), <span class="prelude-val">Some</span>(<span class="number">1</span>));
<span class="comment">// we can still use `iter`, as there are more elements.</span>
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter()%3B%0A%0Aassert_eq!(iter.rposition(%7C%26x%7C%20x%20%3D%3D%202)%2C%20Some(1))%3B%0A%0A%2F%2F%20we%20can%20still%20use%20%60iter%60%2C%20as%20there%20are%20more%20elements.%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0A%7D">Run</a></pre>
</div><h3 id='method.max' class='method'><span id='max.v' class='invisible'><code>fn <a href='#method.max' class='fnname'>max</a>(self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> <span class="where fmt-newline">where<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>, </span></code></span></h3><div class='docblock'><p>Returns the maximum element of an iterator.</p>
<p>If several elements are equally maximum, the last element is
returned. If the iterator is empty, <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is returned.</p>
<h1 id='examples-30' class='section-header'><a href='#examples-30'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">max</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">b</span>.<span class="ident">iter</span>().<span class="ident">max</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Alet%20b%3A%20Vec%3Cu32%3E%20%3D%20Vec%3A%3Anew()%3B%0A%0Aassert_eq!(a.iter().max()%2C%20Some(%263))%3B%0Aassert_eq!(b.iter().max()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.min' class='method'><span id='min.v' class='invisible'><code>fn <a href='#method.min' class='fnname'>min</a>(self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> <span class="where fmt-newline">where<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>, </span></code></span></h3><div class='docblock'><p>Returns the minimum element of an iterator.</p>
<p>If several elements are equally minimum, the first element is
returned. If the iterator is empty, <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is returned.</p>
<h1 id='examples-31' class='section-header'><a href='#examples-31'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">min</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">b</span>.<span class="ident">iter</span>().<span class="ident">min</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Alet%20b%3A%20Vec%3Cu32%3E%20%3D%20Vec%3A%3Anew()%3B%0A%0Aassert_eq!(a.iter().min()%2C%20Some(%261))%3B%0Aassert_eq!(b.iter().min()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.max_by_key' class='method'><span id='max_by_key.v' class='invisible'><code>fn <a href='#method.max_by_key' class='fnname'>max_by_key</a><B, F>(self, f: F) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> <span class="where fmt-newline">where<br> B: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>,<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B, </span></code><div class='since' title='Stable since Rust version 1.6.0'>1.6.0</div></span></h3><div class='docblock'><p>Returns the element that gives the maximum value from the
specified function.</p>
<p>If several elements are equally maximum, the last element is
returned. If the iterator is empty, <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is returned.</p>
<h1 id='examples-32' class='section-header'><a href='#examples-32'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">3_i32</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">5</span>, <span class="op">-</span><span class="number">10</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">max_by_key</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">abs</span>()).<span class="ident">unwrap</span>(), <span class="op">-</span><span class="number">10</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-3_i32%2C%200%2C%201%2C%205%2C%20-10%5D%3B%0Aassert_eq!(*a.iter().max_by_key(%7Cx%7C%20x.abs()).unwrap()%2C%20-10)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.max_by' class='method'><span id='max_by.v' class='invisible'><code>fn <a href='#method.max_by' class='fnname'>max_by</a><F>(self, compare: F) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>, &Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/cmp/enum.Ordering.html" title="enum std::cmp::Ordering">Ordering</a>, </span></code><div class='since' title='Stable since Rust version 1.15.0'>1.15.0</div></span></h3><div class='docblock'><p>Returns the element that gives the maximum value with respect to the
specified comparison function.</p>
<p>If several elements are equally maximum, the last element is
returned. If the iterator is empty, <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is returned.</p>
<h1 id='examples-33' class='section-header'><a href='#examples-33'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">3_i32</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">5</span>, <span class="op">-</span><span class="number">10</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">max_by</span>(<span class="op">|</span><span class="ident">x</span>, <span class="ident">y</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">cmp</span>(<span class="ident">y</span>)).<span class="ident">unwrap</span>(), <span class="number">5</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-3_i32%2C%200%2C%201%2C%205%2C%20-10%5D%3B%0Aassert_eq!(*a.iter().max_by(%7Cx%2C%20y%7C%20x.cmp(y)).unwrap()%2C%205)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.min_by_key' class='method'><span id='min_by_key.v' class='invisible'><code>fn <a href='#method.min_by_key' class='fnname'>min_by_key</a><B, F>(self, f: F) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> <span class="where fmt-newline">where<br> B: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>,<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B, </span></code><div class='since' title='Stable since Rust version 1.6.0'>1.6.0</div></span></h3><div class='docblock'><p>Returns the element that gives the minimum value from the
specified function.</p>
<p>If several elements are equally minimum, the first element is
returned. If the iterator is empty, <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is returned.</p>
<h1 id='examples-34' class='section-header'><a href='#examples-34'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">3_i32</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">5</span>, <span class="op">-</span><span class="number">10</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">min_by_key</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">abs</span>()).<span class="ident">unwrap</span>(), <span class="number">0</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-3_i32%2C%200%2C%201%2C%205%2C%20-10%5D%3B%0Aassert_eq!(*a.iter().min_by_key(%7Cx%7C%20x.abs()).unwrap()%2C%200)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.min_by' class='method'><span id='min_by.v' class='invisible'><code>fn <a href='#method.min_by' class='fnname'>min_by</a><F>(self, compare: F) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>, &Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/cmp/enum.Ordering.html" title="enum std::cmp::Ordering">Ordering</a>, </span></code><div class='since' title='Stable since Rust version 1.15.0'>1.15.0</div></span></h3><div class='docblock'><p>Returns the element that gives the minimum value with respect to the
specified comparison function.</p>
<p>If several elements are equally minimum, the first element is
returned. If the iterator is empty, <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a> is returned.</p>
<h1 id='examples-35' class='section-header'><a href='#examples-35'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="op">-</span><span class="number">3_i32</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">5</span>, <span class="op">-</span><span class="number">10</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">min_by</span>(<span class="op">|</span><span class="ident">x</span>, <span class="ident">y</span><span class="op">|</span> <span class="ident">x</span>.<span class="ident">cmp</span>(<span class="ident">y</span>)).<span class="ident">unwrap</span>(), <span class="op">-</span><span class="number">10</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B-3_i32%2C%200%2C%201%2C%205%2C%20-10%5D%3B%0Aassert_eq!(*a.iter().min_by(%7Cx%2C%20y%7C%20x.cmp(y)).unwrap()%2C%20-10)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.rev' class='method'><span id='rev.v' class='invisible'><code>fn <a href='#method.rev' class='fnname'>rev</a>(self) -> <a class="struct" href="../../std/iter/struct.Rev.html" title="struct std::iter::Rev">Rev</a><Self> <span class="where fmt-newline">where<br> Self: <a class="trait" href="../../std/iter/trait.DoubleEndedIterator.html" title="trait std::iter::DoubleEndedIterator">DoubleEndedIterator</a>, </span></code></span></h3><div class='docblock'><p>Reverses an iterator's direction.</p>
<p>Usually, iterators iterate from left to right. After using <code>rev()</code>,
an iterator will instead iterate from right to left.</p>
<p>This is only possible if the iterator has an end, so <code>rev()</code> only
works on <a href="trait.DoubleEndedIterator.html"><code>DoubleEndedIterator</code></a>s.</p>
<h1 id='examples-36' class='section-header'><a href='#examples-36'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">rev</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20iter%20%3D%20a.iter().rev()%3B%0A%0Aassert_eq!(iter.next()%2C%20Some(%263))%3B%0Aassert_eq!(iter.next()%2C%20Some(%262))%3B%0Aassert_eq!(iter.next()%2C%20Some(%261))%3B%0A%0Aassert_eq!(iter.next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.unzip' class='method'><span id='unzip.v' class='invisible'><code>fn <a href='#method.unzip' class='fnname'>unzip</a><A, B, FromA, FromB>(self) -> <a class="primitive" href="../primitive.tuple.html">(</a>FromA, FromB<a class="primitive" href="../primitive.tuple.html">)</a> <span class="where fmt-newline">where<br> FromA: <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a> + <a class="trait" href="../../std/iter/trait.Extend.html" title="trait std::iter::Extend">Extend</a><A>,<br> FromB: <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a> + <a class="trait" href="../../std/iter/trait.Extend.html" title="trait std::iter::Extend">Extend</a><B>,<br> Self: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = <a class="primitive" href="../primitive.tuple.html">(</a>A, B<a class="primitive" href="../primitive.tuple.html">)</a>>, </span></code></span></h3><div class='docblock'><p>Converts an iterator of pairs into a pair of containers.</p>
<p><code>unzip()</code> consumes an entire iterator of pairs, producing two
collections: one from the left elements of the pairs, and one
from the right elements.</p>
<p>This function is, in some sense, the opposite of <a href="#method.zip"><code>zip</code></a>.</p>
<h1 id='examples-37' class='section-header'><a href='#examples-37'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [(<span class="number">1</span>, <span class="number">2</span>), (<span class="number">3</span>, <span class="number">4</span>)];
<span class="kw">let</span> (<span class="ident">left</span>, <span class="ident">right</span>): (<span class="ident">Vec</span><span class="op"><</span>_<span class="op">></span>, <span class="ident">Vec</span><span class="op"><</span>_<span class="op">></span>) <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">unzip</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">left</span>, [<span class="number">1</span>, <span class="number">3</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">right</span>, [<span class="number">2</span>, <span class="number">4</span>]);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B(1%2C%202)%2C%20(3%2C%204)%5D%3B%0A%0Alet%20(left%2C%20right)%3A%20(Vec%3C_%3E%2C%20Vec%3C_%3E)%20%3D%20a.iter().cloned().unzip()%3B%0A%0Aassert_eq!(left%2C%20%5B1%2C%203%5D)%3B%0Aassert_eq!(right%2C%20%5B2%2C%204%5D)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.cloned' class='method'><span id='cloned.v' class='invisible'><code>fn <a href='#method.cloned' class='fnname'>cloned</a><'a, T>(self) -> <a class="struct" href="../../std/iter/struct.Cloned.html" title="struct std::iter::Cloned">Cloned</a><Self> <span class="where fmt-newline">where<br> Self: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = &'a T>,<br> T: 'a + <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>, </span></code></span></h3><div class='docblock'><p>Creates an iterator which <a href="../../std/clone/trait.Clone.html#tymethod.clone"><code>clone</code></a>s all of its elements.</p>
<p>This is useful when you have an iterator over <code>&T</code>, but you need an
iterator over <code>T</code>.</p>
<h1 id='examples-38' class='section-header'><a href='#examples-38'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">v_cloned</span>: <span class="ident">Vec</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="comment">// cloned is the same as .map(|&x| x), for integers</span>
<span class="kw">let</span> <span class="ident">v_map</span>: <span class="ident">Vec</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span>).<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v_cloned</span>, <span class="macro">vec</span><span class="macro">!</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v_map</span>, <span class="macro">vec</span><span class="macro">!</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20v_cloned%3A%20Vec%3C_%3E%20%3D%20a.iter().cloned().collect()%3B%0A%0A%2F%2F%20cloned%20is%20the%20same%20as%20.map(%7C%26x%7C%20x)%2C%20for%20integers%0Alet%20v_map%3A%20Vec%3C_%3E%20%3D%20a.iter().map(%7C%26x%7C%20x).collect()%3B%0A%0Aassert_eq!(v_cloned%2C%20vec!%5B1%2C%202%2C%203%5D)%3B%0Aassert_eq!(v_map%2C%20vec!%5B1%2C%202%2C%203%5D)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.cycle' class='method'><span id='cycle.v' class='invisible'><code>fn <a href='#method.cycle' class='fnname'>cycle</a>(self) -> <a class="struct" href="../../std/iter/struct.Cycle.html" title="struct std::iter::Cycle">Cycle</a><Self> <span class="where fmt-newline">where<br> Self: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>, </span></code></span></h3><div class='docblock'><p>Repeats an iterator endlessly.</p>
<p>Instead of stopping at <a href="../../std/option/enum.Option.html#variant.None"><code>None</code></a>, the iterator will instead start again,
from the beginning. After iterating again, it will start at the
beginning again. And again. And again. Forever.</p>
<h1 id='examples-39' class='section-header'><a href='#examples-39'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">it</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">cycle</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">it</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">it</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">it</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">it</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">it</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">it</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">3</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">it</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">1</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0A%0Alet%20mut%20it%20%3D%20a.iter().cycle()%3B%0A%0Aassert_eq!(it.next()%2C%20Some(%261))%3B%0Aassert_eq!(it.next()%2C%20Some(%262))%3B%0Aassert_eq!(it.next()%2C%20Some(%263))%3B%0Aassert_eq!(it.next()%2C%20Some(%261))%3B%0Aassert_eq!(it.next()%2C%20Some(%262))%3B%0Aassert_eq!(it.next()%2C%20Some(%263))%3B%0Aassert_eq!(it.next()%2C%20Some(%261))%3B%0A%7D">Run</a></pre>
</div><h3 id='method.sum' class='method'><span id='sum.v' class='invisible'><code>fn <a href='#method.sum' class='fnname'>sum</a><S>(self) -> S <span class="where fmt-newline">where<br> S: <a class="trait" href="../../std/iter/trait.Sum.html" title="trait std::iter::Sum">Sum</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.11.0'>1.11.0</div></span></h3><div class='docblock'><p>Sums the elements of an iterator.</p>
<p>Takes each element, adds them together, and returns the result.</p>
<p>An empty iterator returns the zero value of the type.</p>
<h1 id='panics-4' class='section-header'><a href='#panics-4'>Panics</a></h1>
<p>When calling <code>sum()</code> and a primitive integer type is being returned, this
method will panic if the computation overflows and debug assertions are
enabled.</p>
<h1 id='examples-40' class='section-header'><a href='#examples-40'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">sum</span>: <span class="ident">i32</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">iter</span>().<span class="ident">sum</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">sum</span>, <span class="number">6</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20a%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Alet%20sum%3A%20i32%20%3D%20a.iter().sum()%3B%0A%0Aassert_eq!(sum%2C%206)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.product' class='method'><span id='product.v' class='invisible'><code>fn <a href='#method.product' class='fnname'>product</a><P>(self) -> P <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/iter/trait.Product.html" title="trait std::iter::Product">Product</a><Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.11.0'>1.11.0</div></span></h3><div class='docblock'><p>Iterates over the entire iterator, multiplying all the elements</p>
<p>An empty iterator returns the one value of the type.</p>
<h1 id='panics-5' class='section-header'><a href='#panics-5'>Panics</a></h1>
<p>When calling <code>product()</code> and a primitive integer type is being returned,
method will panic if the computation overflows and debug assertions are
enabled.</p>
<h1 id='examples-41' class='section-header'><a href='#examples-41'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">fn</span> <span class="ident">factorial</span>(<span class="ident">n</span>: <span class="ident">u32</span>) <span class="op">-></span> <span class="ident">u32</span> {
(<span class="number">1</span>..).<span class="ident">take_while</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">i</span><span class="op">|</span> <span class="ident">i</span> <span class="op"><=</span> <span class="ident">n</span>).<span class="ident">product</span>()
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">factorial</span>(<span class="number">0</span>), <span class="number">1</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">factorial</span>(<span class="number">1</span>), <span class="number">1</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">factorial</span>(<span class="number">5</span>), <span class="number">120</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Afn%20factorial(n%3A%20u32)%20-%3E%20u32%20%7B%0A%20%20%20%20(1..).take_while(%7C%26i%7C%20i%20%3C%3D%20n).product()%0A%7D%0Aassert_eq!(factorial(0)%2C%201)%3B%0Aassert_eq!(factorial(1)%2C%201)%3B%0Aassert_eq!(factorial(5)%2C%20120)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.cmp' class='method'><span id='cmp.v' class='invisible'><code>fn <a href='#method.cmp' class='fnname'>cmp</a><I>(self, other: I) -> <a class="enum" href="../../std/cmp/enum.Ordering.html" title="enum std::cmp::Ordering">Ordering</a> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a><Item = Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>, </span></code><div class='since' title='Stable since Rust version 1.5.0'>1.5.0</div></span></h3><div class='docblock'><p>Lexicographically compares the elements of this <code>Iterator</code> with those
of another.</p>
</div><h3 id='method.partial_cmp' class='method'><span id='partial_cmp.v' class='invisible'><code>fn <a href='#method.partial_cmp' class='fnname'>partial_cmp</a><I>(self, other: I) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="enum" href="../../std/cmp/enum.Ordering.html" title="enum std::cmp::Ordering">Ordering</a>> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.5.0'>1.5.0</div></span></h3><div class='docblock'><p>Lexicographically compares the elements of this <code>Iterator</code> with those
of another.</p>
</div><h3 id='method.eq' class='method'><span id='eq.v' class='invisible'><code>fn <a href='#method.eq' class='fnname'>eq</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialEq.html" title="trait std::cmp::PartialEq">PartialEq</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.5.0'>1.5.0</div></span></h3><div class='docblock'><p>Determines if the elements of this <code>Iterator</code> are equal to those of
another.</p>
</div><h3 id='method.ne' class='method'><span id='ne.v' class='invisible'><code>fn <a href='#method.ne' class='fnname'>ne</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialEq.html" title="trait std::cmp::PartialEq">PartialEq</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.5.0'>1.5.0</div></span></h3><div class='docblock'><p>Determines if the elements of this <code>Iterator</code> are unequal to those of
another.</p>
</div><h3 id='method.lt' class='method'><span id='lt.v' class='invisible'><code>fn <a href='#method.lt' class='fnname'>lt</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.5.0'>1.5.0</div></span></h3><div class='docblock'><p>Determines if the elements of this <code>Iterator</code> are lexicographically
less than those of another.</p>
</div><h3 id='method.le' class='method'><span id='le.v' class='invisible'><code>fn <a href='#method.le' class='fnname'>le</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.5.0'>1.5.0</div></span></h3><div class='docblock'><p>Determines if the elements of this <code>Iterator</code> are lexicographically
less or equal to those of another.</p>
</div><h3 id='method.gt' class='method'><span id='gt.v' class='invisible'><code>fn <a href='#method.gt' class='fnname'>gt</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.5.0'>1.5.0</div></span></h3><div class='docblock'><p>Determines if the elements of this <code>Iterator</code> are lexicographically
greater than those of another.</p>
</div><h3 id='method.ge' class='method'><span id='ge.v' class='invisible'><code>fn <a href='#method.ge' class='fnname'>ge</a><I>(self, other: I) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>,<br> Self::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>: <a class="trait" href="../../std/cmp/trait.PartialOrd.html" title="trait std::cmp::PartialOrd">PartialOrd</a><<I as <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>>::<a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">Item</a>>, </span></code><div class='since' title='Stable since Rust version 1.5.0'>1.5.0</div></span></h3><div class='docblock'><p>Determines if the elements of this <code>Iterator</code> are lexicographically
greater than or equal to those of another.</p>
</div></div>
<h2 id='implementors'>Implementors</h2>
<ul class='item-list' id='implementors-list'>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>, </span></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/char/struct.ToUppercase.html" title="struct std::char::ToUppercase">ToUppercase</a></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/char/struct.DecodeUtf16.html" title="struct std::char::DecodeUtf16">DecodeUtf16</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = <a class="primitive" href="../primitive.u16.html">u16</a>>, </span></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std_unicode/u_str/struct.Utf16Encoder.html" title="struct std_unicode::u_str::Utf16Encoder">Utf16Encoder</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = <a class="primitive" href="../primitive.char.html">char</a>>, </span></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/char/struct.ToLowercase.html" title="struct std::char::ToLowercase">ToLowercase</a></code></li>
<li><code>impl<'a> Iterator for <a class="struct" href="../../std/str/struct.SplitWhitespace.html" title="struct std::str::SplitWhitespace">SplitWhitespace</a><'a></code></li>
<li><code>impl<'a> Iterator for std::string::<a class="struct" href="../../std/string/struct.Drain.html" title="struct std::string::Drain">Drain</a><'a></code></li>
<li><code>impl<'a, T> Iterator for std::collections::btree_set::<a class="struct" href="../../std/collections/btree_set/struct.Union.html" title="struct std::collections::btree_set::Union">Union</a><'a, T> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>, </span></code></li>
<li><code>impl<T> Iterator for std::collections::btree_set::<a class="struct" href="../../std/collections/btree_set/struct.IntoIter.html" title="struct std::collections::btree_set::IntoIter">IntoIter</a><T></code></li>
<li><code>impl<'a, T> Iterator for std::vec::<a class="struct" href="../../std/vec/struct.Drain.html" title="struct std::vec::Drain">Drain</a><'a, T></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::btree_map::<a class="struct" href="../../std/collections/btree_map/struct.Values.html" title="struct std::collections::btree_map::Values">Values</a><'a, K, V></code></li>
<li><code>impl<T> Iterator for std::collections::vec_deque::<a class="struct" href="../../std/collections/vec_deque/struct.IntoIter.html" title="struct std::collections::vec_deque::IntoIter">IntoIter</a><T></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::btree_map::<a class="struct" href="../../std/collections/btree_map/struct.IterMut.html" title="struct std::collections::btree_map::IterMut">IterMut</a><'a, K, V> <span class="where fmt-newline">where<br> K: 'a,<br> V: 'a, </span></code></li>
<li><code>impl<K, V> Iterator for std::collections::btree_map::<a class="struct" href="../../std/collections/btree_map/struct.IntoIter.html" title="struct std::collections::btree_map::IntoIter">IntoIter</a><K, V></code></li>
<li><code>impl<'a, K, V> Iterator for <a class="struct" href="../../std/collections/btree_map/struct.RangeMut.html" title="struct std::collections::btree_map::RangeMut">RangeMut</a><'a, K, V></code></li>
<li><code>impl<'a, T> Iterator for std::collections::btree_set::<a class="struct" href="../../std/collections/btree_set/struct.Range.html" title="struct std::collections::btree_set::Range">Range</a><'a, T></code></li>
<li><code>impl<'a> Iterator for <a class="struct" href="../../std/str/struct.EncodeUtf16.html" title="struct std::str::EncodeUtf16">EncodeUtf16</a><'a></code></li>
<li><code>impl<T> Iterator for std::collections::binary_heap::<a class="struct" href="../../std/collections/binary_heap/struct.IntoIter.html" title="struct std::collections::binary_heap::IntoIter">IntoIter</a><T></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::btree_map::<a class="struct" href="../../std/collections/btree_map/struct.Keys.html" title="struct std::collections::btree_map::Keys">Keys</a><'a, K, V></code></li>
<li><code>impl<'a, T> Iterator for std::collections::binary_heap::<a class="struct" href="../../std/collections/binary_heap/struct.Iter.html" title="struct std::collections::binary_heap::Iter">Iter</a><'a, T></code></li>
<li><code>impl<'a, T> Iterator for std::collections::vec_deque::<a class="struct" href="../../std/collections/vec_deque/struct.IterMut.html" title="struct std::collections::vec_deque::IterMut">IterMut</a><'a, T></code></li>
<li><code>impl<'a, T> Iterator for std::collections::btree_set::<a class="struct" href="../../std/collections/btree_set/struct.Iter.html" title="struct std::collections::btree_set::Iter">Iter</a><'a, T></code></li>
<li><code>impl<'a, T> Iterator for std::collections::linked_list::<a class="struct" href="../../std/collections/linked_list/struct.IterMut.html" title="struct std::collections::linked_list::IterMut">IterMut</a><'a, T></code></li>
<li><code>impl<'a, I> Iterator for std::vec::<a class="struct" href="../../std/vec/struct.Splice.html" title="struct std::vec::Splice">Splice</a><'a, I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a, T> Iterator for std::collections::linked_list::<a class="struct" href="../../std/collections/linked_list/struct.Iter.html" title="struct std::collections::linked_list::Iter">Iter</a><'a, T></code></li>
<li><code>impl<'a, T> Iterator for std::collections::btree_set::<a class="struct" href="../../std/collections/btree_set/struct.SymmetricDifference.html" title="struct std::collections::btree_set::SymmetricDifference">SymmetricDifference</a><'a, T> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>, </span></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::btree_map::<a class="struct" href="../../std/collections/btree_map/struct.ValuesMut.html" title="struct std::collections::btree_map::ValuesMut">ValuesMut</a><'a, K, V></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::btree_map::<a class="struct" href="../../std/collections/btree_map/struct.Iter.html" title="struct std::collections::btree_map::Iter">Iter</a><'a, K, V> <span class="where fmt-newline">where<br> K: 'a,<br> V: 'a, </span></code></li>
<li><code>impl<T> Iterator for std::collections::linked_list::<a class="struct" href="../../std/collections/linked_list/struct.IntoIter.html" title="struct std::collections::linked_list::IntoIter">IntoIter</a><T></code></li>
<li><code>impl<T> Iterator for std::vec::<a class="struct" href="../../std/vec/struct.IntoIter.html" title="struct std::vec::IntoIter">IntoIter</a><T></code></li>
<li><code>impl<'a, T> Iterator for std::collections::vec_deque::<a class="struct" href="../../std/collections/vec_deque/struct.Drain.html" title="struct std::collections::vec_deque::Drain">Drain</a><'a, T> <span class="where fmt-newline">where<br> T: 'a, </span></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::btree_map::<a class="struct" href="../../std/collections/btree_map/struct.Range.html" title="struct std::collections::btree_map::Range">Range</a><'a, K, V></code></li>
<li><code>impl<'a, 'b> Iterator for std::string::<a class="struct" href="../../std/string/struct.Splice.html" title="struct std::string::Splice">Splice</a><'a, 'b></code></li>
<li><code>impl<'a, T> Iterator for std::collections::btree_set::<a class="struct" href="../../std/collections/btree_set/struct.Difference.html" title="struct std::collections::btree_set::Difference">Difference</a><'a, T> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>, </span></code></li>
<li><code>impl<'a, T> Iterator for std::collections::btree_set::<a class="struct" href="../../std/collections/btree_set/struct.Intersection.html" title="struct std::collections::btree_set::Intersection">Intersection</a><'a, T> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/cmp/trait.Ord.html" title="trait std::cmp::Ord">Ord</a>, </span></code></li>
<li><code>impl<'a, T> Iterator for std::collections::binary_heap::<a class="struct" href="../../std/collections/binary_heap/struct.Drain.html" title="struct std::collections::binary_heap::Drain">Drain</a><'a, T> <span class="where fmt-newline">where<br> T: 'a, </span></code></li>
<li><code>impl<'a, T> Iterator for std::collections::vec_deque::<a class="struct" href="../../std/collections/vec_deque/struct.Iter.html" title="struct std::collections::vec_deque::Iter">Iter</a><'a, T></code></li>
<li><code>impl<A> Iterator for std::iter::<a class="struct" href="../../std/iter/struct.DeprecatedStepBy.html" title="struct std::iter::DeprecatedStepBy">DeprecatedStepBy</a><A, <a class="struct" href="../../std/ops/struct.RangeInclusive.html" title="struct std::ops::RangeInclusive">RangeInclusive</a><A>> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a> + <a class="trait" href="../../std/iter/trait.Step.html" title="trait std::iter::Step">Step</a>, </span></code></li>
<li><code>impl<'a> Iterator for std::str::<a class="struct" href="../../std/str/struct.Chars.html" title="struct std::str::Chars">Chars</a><'a></code></li>
<li><code>impl<'a, P> Iterator for std::str::<a class="struct" href="../../std/str/struct.RSplitN.html" title="struct std::str::RSplitN">RSplitN</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>,<br> <P as <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>>::<a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Searcher</a>: <a class="trait" href="../../std/str/pattern/trait.ReverseSearcher.html" title="trait std::str::pattern::ReverseSearcher">ReverseSearcher</a><'a>, </span></code></li>
<li><code>impl<'a, A> Iterator for std::option::<a class="struct" href="../../std/option/struct.Iter.html" title="struct std::option::Iter">Iter</a><'a, A></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/char/struct.EscapeDebug.html" title="struct std::char::EscapeDebug">EscapeDebug</a></code></li>
<li><code>impl<T> Iterator for <a class="struct" href="../../std/iter/struct.Empty.html" title="struct std::iter::Empty">Empty</a><T></code></li>
<li><code>impl<B, I, St, F> Iterator for <a class="struct" href="../../std/iter/struct.Scan.html" title="struct std::iter::Scan">Scan</a><I, St, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&mut St, <I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><B>,<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a, T, P> Iterator for std::slice::<a class="struct" href="../../std/slice/struct.RSplitN.html" title="struct std::slice::RSplitN">RSplitN</a><'a, T, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<'a, T> Iterator for std::slice::<a class="struct" href="../../std/slice/struct.IterMut.html" title="struct std::slice::IterMut">IterMut</a><'a, T></code></li>
<li><code>impl<A> Iterator for std::iter::<a class="struct" href="../../std/iter/struct.DeprecatedStepBy.html" title="struct std::iter::DeprecatedStepBy">DeprecatedStepBy</a><A, <a class="struct" href="../../std/ops/struct.Range.html" title="struct std::ops::Range">Range</a><A>> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a> + <a class="trait" href="../../std/iter/trait.Step.html" title="trait std::iter::Step">Step</a>, </span></code></li>
<li><code>impl<'a, T> Iterator for std::result::<a class="struct" href="../../std/result/struct.Iter.html" title="struct std::result::Iter">Iter</a><'a, T></code></li>
<li><code>impl<B, I, F> Iterator for <a class="struct" href="../../std/iter/struct.Map.html" title="struct std::iter::Map">Map</a><I, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(<I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> B,<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/iter/struct.Take.html" title="struct std::iter::Take">Take</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a, P> Iterator for std::str::<a class="struct" href="../../std/str/struct.Split.html" title="struct std::str::Split">Split</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>, </span></code></li>
<li><code>impl<'a, I, T> Iterator for <a class="struct" href="../../std/iter/struct.Cloned.html" title="struct std::iter::Cloned">Cloned</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = &'a T>,<br> T: 'a + <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>, </span></code></li>
<li><code>impl<'a, T> Iterator for <a class="struct" href="../../std/slice/struct.Chunks.html" title="struct std::slice::Chunks">Chunks</a><'a, T></code></li>
<li><code>impl<'a, T, P> Iterator for std::slice::<a class="struct" href="../../std/slice/struct.RSplit.html" title="struct std::slice::RSplit">RSplit</a><'a, T, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<'a, P> Iterator for std::str::<a class="struct" href="../../std/str/struct.SplitN.html" title="struct std::str::SplitN">SplitN</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>, </span></code></li>
<li><code>impl<'a, T, P> Iterator for std::slice::<a class="struct" href="../../std/slice/struct.Split.html" title="struct std::slice::Split">Split</a><'a, T, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<A> Iterator for std::option::<a class="struct" href="../../std/option/struct.IntoIter.html" title="struct std::option::IntoIter">IntoIter</a><A></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/iter/struct.Fuse.html" title="struct std::iter::Fuse">Fuse</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.FusedIterator.html" title="trait std::iter::FusedIterator">FusedIterator</a>, </span></code></li>
<li><code>impl<'a, A> Iterator for std::option::<a class="struct" href="../../std/option/struct.IterMut.html" title="struct std::option::IterMut">IterMut</a><'a, A></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/iter/struct.Cycle.html" title="struct std::iter::Cycle">Cycle</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a> + <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a, P> Iterator for <a class="struct" href="../../std/str/struct.MatchIndices.html" title="struct std::str::MatchIndices">MatchIndices</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>, </span></code></li>
<li><code>impl<'a, P> Iterator for <a class="struct" href="../../std/str/struct.Matches.html" title="struct std::str::Matches">Matches</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>, </span></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/iter/struct.Rev.html" title="struct std::iter::Rev">Rev</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.DoubleEndedIterator.html" title="trait std::iter::DoubleEndedIterator">DoubleEndedIterator</a>, </span></code></li>
<li><code>impl<'a, T> Iterator for std::result::<a class="struct" href="../../std/result/struct.IterMut.html" title="struct std::result::IterMut">IterMut</a><'a, T></code></li>
<li><code>impl<I> Iterator for std::iter::<a class="struct" href="../../std/iter/struct.StepBy.html" title="struct std::iter::StepBy">StepBy</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a, I> Iterator for &'a mut I <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a> + ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>, </span></code></li>
<li><code>impl<'a> Iterator for std::str::<a class="struct" href="../../std/str/struct.Lines.html" title="struct std::str::Lines">Lines</a><'a></code></li>
<li><code>impl<B, I, F> Iterator for <a class="struct" href="../../std/iter/struct.FilterMap.html" title="struct std::iter::FilterMap">FilterMap</a><I, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(<I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><B>,<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<A> Iterator for <a class="struct" href="../../std/ops/struct.RangeFrom.html" title="struct std::ops::RangeFrom">RangeFrom</a><A> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/iter/trait.Step.html" title="trait std::iter::Step">Step</a>,<br> &'a A: <a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Add</a><&'a A>,<br> <&'a A as <a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Add</a><&'a A>>::<a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Output</a> == A, </span></code></li>
<li><code>impl<I, F> Iterator for <a class="struct" href="../../std/iter/struct.Inspect.html" title="struct std::iter::Inspect">Inspect</a><I, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&<I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.tuple.html">()</a>,<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a, T, P> Iterator for <a class="struct" href="../../std/slice/struct.SplitMut.html" title="struct std::slice::SplitMut">SplitMut</a><'a, T, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<'a> Iterator for <a class="struct" href="../../std/str/struct.LinesAny.html" title="struct std::str::LinesAny">LinesAny</a><'a></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/iter/struct.Peekable.html" title="struct std::iter::Peekable">Peekable</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<I, U, F> Iterator for <a class="struct" href="../../std/iter/struct.FlatMap.html" title="struct std::iter::FlatMap">FlatMap</a><I, U, F> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(<I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> U,<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>,<br> U: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a>, </span></code></li>
<li><code>impl<A> Iterator for std::iter::<a class="struct" href="../../std/iter/struct.DeprecatedStepBy.html" title="struct std::iter::DeprecatedStepBy">DeprecatedStepBy</a><A, <a class="struct" href="../../std/ops/struct.RangeFrom.html" title="struct std::ops::RangeFrom">RangeFrom</a><A>> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>,<br> &'a A: <a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Add</a><&'a A>,<br> <&'a A as <a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Add</a><&'a A>>::<a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Output</a> == A, </span></code></li>
<li><code>impl<'a, T> Iterator for <a class="struct" href="../../std/slice/struct.Windows.html" title="struct std::slice::Windows">Windows</a><'a, T></code></li>
<li><code>impl<'a, T, P> Iterator for std::slice::<a class="struct" href="../../std/slice/struct.SplitN.html" title="struct std::slice::SplitN">SplitN</a><'a, T, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<I, P> Iterator for <a class="struct" href="../../std/iter/struct.SkipWhile.html" title="struct std::iter::SkipWhile">SkipWhile</a><I, P> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>,<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&<I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<'a, T, P> Iterator for <a class="struct" href="../../std/slice/struct.RSplitNMut.html" title="struct std::slice::RSplitNMut">RSplitNMut</a><'a, T, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<'a, P> Iterator for <a class="struct" href="../../std/str/struct.RMatchIndices.html" title="struct std::str::RMatchIndices">RMatchIndices</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>,<br> <P as <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>>::<a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Searcher</a>: <a class="trait" href="../../std/str/pattern/trait.ReverseSearcher.html" title="trait std::str::pattern::ReverseSearcher">ReverseSearcher</a><'a>, </span></code></li>
<li><code>impl<A> Iterator for <a class="struct" href="../../std/ops/struct.RangeInclusive.html" title="struct std::ops::RangeInclusive">RangeInclusive</a><A> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/iter/trait.Step.html" title="trait std::iter::Step">Step</a>,<br> &'a A: <a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Add</a><&'a A>,<br> <&'a A as <a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Add</a><&'a A>>::<a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Output</a> == A, </span></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/iter/struct.Fuse.html" title="struct std::iter::Fuse">Fuse</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a> Iterator for <a class="struct" href="../../std/str/struct.CharIndices.html" title="struct std::str::CharIndices">CharIndices</a><'a></code></li>
<li><code>impl<T> Iterator for std::result::<a class="struct" href="../../std/result/struct.IntoIter.html" title="struct std::result::IntoIter">IntoIter</a><T></code></li>
<li><code>impl<A, B> Iterator for <a class="struct" href="../../std/iter/struct.Zip.html" title="struct std::iter::Zip">Zip</a><A, B> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>,<br> B: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a, T> Iterator for std::slice::<a class="struct" href="../../std/slice/struct.Iter.html" title="struct std::slice::Iter">Iter</a><'a, T></code></li>
<li><code>impl<A> Iterator for <a class="struct" href="../../std/iter/struct.Repeat.html" title="struct std::iter::Repeat">Repeat</a><A> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>, </span></code></li>
<li><code>impl<'a, P> Iterator for <a class="struct" href="../../std/str/struct.RSplitTerminator.html" title="struct std::str::RSplitTerminator">RSplitTerminator</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>,<br> <P as <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>>::<a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Searcher</a>: <a class="trait" href="../../std/str/pattern/trait.ReverseSearcher.html" title="trait std::str::pattern::ReverseSearcher">ReverseSearcher</a><'a>, </span></code></li>
<li><code>impl<I, P> Iterator for <a class="struct" href="../../std/iter/struct.Filter.html" title="struct std::iter::Filter">Filter</a><I, P> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>,<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&<I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/char/struct.DecodeUtf8.html" title="struct std::char::DecodeUtf8">DecodeUtf8</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = <a class="primitive" href="../primitive.u8.html">u8</a>>, </span></code></li>
<li><code>impl Iterator for std::char::<a class="struct" href="../../std/char/struct.EscapeDefault.html" title="struct std::char::EscapeDefault">EscapeDefault</a></code></li>
<li><code>impl<'a> Iterator for std::str::<a class="struct" href="../../std/str/struct.Bytes.html" title="struct std::str::Bytes">Bytes</a><'a></code></li>
<li><code>impl<'a, T, P> Iterator for <a class="struct" href="../../std/slice/struct.RSplitMut.html" title="struct std::slice::RSplitMut">RSplitMut</a><'a, T, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<T> Iterator for <a class="struct" href="../../std/iter/struct.Once.html" title="struct std::iter::Once">Once</a><T></code></li>
<li><code>impl<'a, T, P> Iterator for <a class="struct" href="../../std/slice/struct.SplitNMut.html" title="struct std::slice::SplitNMut">SplitNMut</a><'a, T, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<A, B> Iterator for <a class="struct" href="../../std/iter/struct.Chain.html" title="struct std::iter::Chain">Chain</a><A, B> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>,<br> B: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a><Item = <A as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>>, </span></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/iter/struct.Enumerate.html" title="struct std::iter::Enumerate">Enumerate</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/char/struct.EscapeUnicode.html" title="struct std::char::EscapeUnicode">EscapeUnicode</a></code></li>
<li><code>impl<A> Iterator for std::ops::<a class="struct" href="../../std/ops/struct.Range.html" title="struct std::ops::Range">Range</a><A> <span class="where fmt-newline">where<br> A: <a class="trait" href="../../std/iter/trait.Step.html" title="trait std::iter::Step">Step</a>,<br> &'a A: <a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Add</a><&'a A>,<br> <&'a A as <a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Add</a><&'a A>>::<a class="trait" href="../../std/ops/trait.Add.html" title="trait std::ops::Add">Output</a> == A, </span></code></li>
<li><code>impl<'a, P> Iterator for std::str::<a class="struct" href="../../std/str/struct.RSplit.html" title="struct std::str::RSplit">RSplit</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>,<br> <P as <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>>::<a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Searcher</a>: <a class="trait" href="../../std/str/pattern/trait.ReverseSearcher.html" title="trait std::str::pattern::ReverseSearcher">ReverseSearcher</a><'a>, </span></code></li>
<li><code>impl<'a, T> Iterator for <a class="struct" href="../../std/slice/struct.ChunksMut.html" title="struct std::slice::ChunksMut">ChunksMut</a><'a, T></code></li>
<li><code>impl<'a, P> Iterator for <a class="struct" href="../../std/str/struct.SplitTerminator.html" title="struct std::str::SplitTerminator">SplitTerminator</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>, </span></code></li>
<li><code>impl<I, P> Iterator for <a class="struct" href="../../std/iter/struct.TakeWhile.html" title="struct std::iter::TakeWhile">TakeWhile</a><I, P> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>,<br> P: <a class="trait" href="../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>(&<I as <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>>::<a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Item</a>) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code></li>
<li><code>impl<I> Iterator for <a class="struct" href="../../std/iter/struct.Skip.html" title="struct std::iter::Skip">Skip</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../std/iter/trait.Iterator.html" title="trait std::iter::Iterator">Iterator</a>, </span></code></li>
<li><code>impl<'a, P> Iterator for <a class="struct" href="../../std/str/struct.RMatches.html" title="struct std::str::RMatches">RMatches</a><'a, P> <span class="where fmt-newline">where<br> P: <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>,<br> <P as <a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Pattern</a><'a>>::<a class="trait" href="../../std/str/pattern/trait.Pattern.html" title="trait std::str::pattern::Pattern">Searcher</a>: <a class="trait" href="../../std/str/pattern/trait.ReverseSearcher.html" title="trait std::str::pattern::ReverseSearcher">ReverseSearcher</a><'a>, </span></code></li>
<li><code>impl<'a, T, R> Iterator for <a class="struct" href="https://doc.rust-lang.org/nightly/rand/struct.Generator.html" title="struct rand::Generator">Generator</a><'a, T, R> <span class="where fmt-newline">where<br> R: <a class="trait" href="https://doc.rust-lang.org/nightly/rand/trait.Rng.html" title="trait rand::Rng">Rng</a>,<br> T: Rand, </span></code></li>
<li><code>impl<'a, R> Iterator for <a class="struct" href="https://doc.rust-lang.org/nightly/rand/struct.AsciiGenerator.html" title="struct rand::AsciiGenerator">AsciiGenerator</a><'a, R> <span class="where fmt-newline">where<br> R: <a class="trait" href="https://doc.rust-lang.org/nightly/rand/trait.Rng.html" title="trait rand::Rng">Rng</a>, </span></code></li>
<li><code>impl Iterator for std::ascii::<a class="struct" href="../../std/ascii/struct.EscapeDefault.html" title="struct std::ascii::EscapeDefault">EscapeDefault</a></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::hash_map::<a class="struct" href="../../std/collections/hash_map/struct.Iter.html" title="struct std::collections::hash_map::Iter">Iter</a><'a, K, V></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::hash_map::<a class="struct" href="../../std/collections/hash_map/struct.IterMut.html" title="struct std::collections::hash_map::IterMut">IterMut</a><'a, K, V></code></li>
<li><code>impl<K, V> Iterator for std::collections::hash_map::<a class="struct" href="../../std/collections/hash_map/struct.IntoIter.html" title="struct std::collections::hash_map::IntoIter">IntoIter</a><K, V></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::hash_map::<a class="struct" href="../../std/collections/hash_map/struct.Keys.html" title="struct std::collections::hash_map::Keys">Keys</a><'a, K, V></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::hash_map::<a class="struct" href="../../std/collections/hash_map/struct.Values.html" title="struct std::collections::hash_map::Values">Values</a><'a, K, V></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::hash_map::<a class="struct" href="../../std/collections/hash_map/struct.ValuesMut.html" title="struct std::collections::hash_map::ValuesMut">ValuesMut</a><'a, K, V></code></li>
<li><code>impl<'a, K, V> Iterator for std::collections::hash_map::<a class="struct" href="../../std/collections/hash_map/struct.Drain.html" title="struct std::collections::hash_map::Drain">Drain</a><'a, K, V></code></li>
<li><code>impl<'a, K> Iterator for std::collections::hash_set::<a class="struct" href="../../std/collections/hash_set/struct.Iter.html" title="struct std::collections::hash_set::Iter">Iter</a><'a, K></code></li>
<li><code>impl<K> Iterator for std::collections::hash_set::<a class="struct" href="../../std/collections/hash_set/struct.IntoIter.html" title="struct std::collections::hash_set::IntoIter">IntoIter</a><K></code></li>
<li><code>impl<'a, K> Iterator for std::collections::hash_set::<a class="struct" href="../../std/collections/hash_set/struct.Drain.html" title="struct std::collections::hash_set::Drain">Drain</a><'a, K></code></li>
<li><code>impl<'a, T, S> Iterator for std::collections::hash_set::<a class="struct" href="../../std/collections/hash_set/struct.Intersection.html" title="struct std::collections::hash_set::Intersection">Intersection</a><'a, T, S> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a> + <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a>, </span></code></li>
<li><code>impl<'a, T, S> Iterator for std::collections::hash_set::<a class="struct" href="../../std/collections/hash_set/struct.Difference.html" title="struct std::collections::hash_set::Difference">Difference</a><'a, T, S> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a> + <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a>, </span></code></li>
<li><code>impl<'a, T, S> Iterator for std::collections::hash_set::<a class="struct" href="../../std/collections/hash_set/struct.SymmetricDifference.html" title="struct std::collections::hash_set::SymmetricDifference">SymmetricDifference</a><'a, T, S> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a> + <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a>, </span></code></li>
<li><code>impl<'a, T, S> Iterator for std::collections::hash_set::<a class="struct" href="../../std/collections/hash_set/struct.Union.html" title="struct std::collections::hash_set::Union">Union</a><'a, T, S> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a> + <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a>, </span></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/env/struct.Vars.html" title="struct std::env::Vars">Vars</a></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/env/struct.VarsOs.html" title="struct std::env::VarsOs">VarsOs</a></code></li>
<li><code>impl<'a> Iterator for <a class="struct" href="../../std/env/struct.SplitPaths.html" title="struct std::env::SplitPaths">SplitPaths</a><'a></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/env/struct.Args.html" title="struct std::env::Args">Args</a></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/env/struct.ArgsOs.html" title="struct std::env::ArgsOs">ArgsOs</a></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/fs/struct.ReadDir.html" title="struct std::fs::ReadDir">ReadDir</a></code></li>
<li><code>impl<R: <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a>> Iterator for std::io::<a class="struct" href="../../std/io/struct.Bytes.html" title="struct std::io::Bytes">Bytes</a><R></code></li>
<li><code>impl<R: <a class="trait" href="../../std/io/trait.Read.html" title="trait std::io::Read">Read</a>> Iterator for std::io::<a class="struct" href="../../std/io/struct.Chars.html" title="struct std::io::Chars">Chars</a><R></code></li>
<li><code>impl<B: <a class="trait" href="../../std/io/trait.BufRead.html" title="trait std::io::BufRead">BufRead</a>> Iterator for std::io::<a class="struct" href="../../std/io/struct.Split.html" title="struct std::io::Split">Split</a><B></code></li>
<li><code>impl<B: <a class="trait" href="../../std/io/trait.BufRead.html" title="trait std::io::BufRead">BufRead</a>> Iterator for std::io::<a class="struct" href="../../std/io/struct.Lines.html" title="struct std::io::Lines">Lines</a><B></code></li>
<li><code>impl<'a> Iterator for std::net::<a class="struct" href="../../std/net/struct.Incoming.html" title="struct std::net::Incoming">Incoming</a><'a></code></li>
<li><code>impl Iterator for <a class="struct" href="../../std/net/struct.LookupHost.html" title="struct std::net::LookupHost">LookupHost</a></code></li>
<li><code>impl<'a> Iterator for std::path::<a class="struct" href="../../std/path/struct.Iter.html" title="struct std::path::Iter">Iter</a><'a></code></li>
<li><code>impl<'a> Iterator for <a class="struct" href="../../std/path/struct.Components.html" title="struct std::path::Components">Components</a><'a></code></li>
<li><code>impl<'a, T> Iterator for std::sync::mpsc::<a class="struct" href="../../std/sync/mpsc/struct.Iter.html" title="struct std::sync::mpsc::Iter">Iter</a><'a, T></code></li>
<li><code>impl<'a, T> Iterator for <a class="struct" href="../../std/sync/mpsc/struct.TryIter.html" title="struct std::sync::mpsc::TryIter">TryIter</a><'a, T></code></li>
<li><code>impl<T> Iterator for std::sync::mpsc::<a class="struct" href="../../std/sync/mpsc/struct.IntoIter.html" title="struct std::sync::mpsc::IntoIter">IntoIter</a><T></code></li>
<li><code>impl<'a> Iterator for std::os::unix::net::<a class="struct" href="../../std/os/unix/net/struct.Incoming.html" title="struct std::os::unix::net::Incoming">Incoming</a><'a></code></li>
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