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<p class='location'>Struct HashSet</p><div class="block items"><ul><li><a href="#methods">Methods</a></li><li><a href="#implementations">Trait Implementations</a></li></ul></div><p class='location'><a href='../index.html'>std</a>::<wbr><a href='index.html'>collections</a></p><script>window.sidebarCurrent = {name: 'HashSet', ty: 'struct', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<h1 class='fqn'><span class='in-band'>Struct <a href='../index.html'>std</a>::<wbr><a href='index.html'>collections</a>::<wbr><a class="struct" href=''>HashSet</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>]
</a>
</span><a class='srclink' href='../../src/std/collections/hash/set.rs.html#121-123' title='goto source code'>[src]</a></span></h1>
<pre class='rust struct'>pub struct HashSet<T, S = <a class="struct" href="../../std/collections/hash_map/struct.RandomState.html" title="struct std::collections::hash_map::RandomState">RandomState</a>> { /* fields omitted */ }</pre><div class='docblock'><p>A hash set implemented as a <code>HashMap</code> where the value is <code>()</code>.</p>
<p>As with the <a href="struct.HashMap.html"><code>HashMap</code></a> type, a <code>HashSet</code> requires that the elements
implement the <a href="../../std/cmp/trait.Eq.html"><code>Eq</code></a> and <a href="../../std/hash/trait.Hash.html"><code>Hash</code></a> traits. This can frequently be achieved by
using <code>#[derive(PartialEq, Eq, Hash)]</code>. If you implement these yourself,
it is important that the following property holds:</p>
<pre><code class="language-text">k1 == k2 -> hash(k1) == hash(k2)
</code></pre>
<p>In other words, if two keys are equal, their hashes must be equal.</p>
<p>It is a logic error for an item to be modified in such a way that the
item's hash, as determined by the <a href="../../std/hash/trait.Hash.html"><code>Hash</code></a> trait, or its equality, as
determined by the <a href="../../std/cmp/trait.Eq.html"><code>Eq</code></a> trait, changes while it is in the set. This is
normally only possible through <a href="../../std/cell/struct.Cell.html"><code>Cell</code></a>, <a href="../../std/cell/struct.RefCell.html"><code>RefCell</code></a>, global state, I/O, or
unsafe code.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="comment">// Type inference lets us omit an explicit type signature (which</span>
<span class="comment">// would be `HashSet<&str>` in this example).</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">books</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="comment">// Add some books.</span>
<span class="ident">books</span>.<span class="ident">insert</span>(<span class="string">"A Dance With Dragons"</span>);
<span class="ident">books</span>.<span class="ident">insert</span>(<span class="string">"To Kill a Mockingbird"</span>);
<span class="ident">books</span>.<span class="ident">insert</span>(<span class="string">"The Odyssey"</span>);
<span class="ident">books</span>.<span class="ident">insert</span>(<span class="string">"The Great Gatsby"</span>);
<span class="comment">// Check for a specific one.</span>
<span class="kw">if</span> <span class="op">!</span><span class="ident">books</span>.<span class="ident">contains</span>(<span class="string">"The Winds of Winter"</span>) {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"We have {} books, but The Winds of Winter ain't one."</span>,
<span class="ident">books</span>.<span class="ident">len</span>());
}
<span class="comment">// Remove a book.</span>
<span class="ident">books</span>.<span class="ident">remove</span>(<span class="string">"The Odyssey"</span>);
<span class="comment">// Iterate over everything.</span>
<span class="kw">for</span> <span class="ident">book</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">books</span> {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">book</span>);
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%2F%2F%20Type%20inference%20lets%20us%20omit%20an%20explicit%20type%20signature%20(which%0A%2F%2F%20would%20be%20%60HashSet%3C%26str%3E%60%20in%20this%20example).%0Alet%20mut%20books%20%3D%20HashSet%3A%3Anew()%3B%0A%0A%2F%2F%20Add%20some%20books.%0Abooks.insert(%22A%20Dance%20With%20Dragons%22)%3B%0Abooks.insert(%22To%20Kill%20a%20Mockingbird%22)%3B%0Abooks.insert(%22The%20Odyssey%22)%3B%0Abooks.insert(%22The%20Great%20Gatsby%22)%3B%0A%0A%2F%2F%20Check%20for%20a%20specific%20one.%0Aif%20!books.contains(%22The%20Winds%20of%20Winter%22)%20%7B%0A%20%20%20%20println!(%22We%20have%20%7B%7D%20books%2C%20but%20The%20Winds%20of%20Winter%20ain't%20one.%22%2C%0A%20%20%20%20%20%20%20%20%20%20%20%20%20books.len())%3B%0A%7D%0A%0A%2F%2F%20Remove%20a%20book.%0Abooks.remove(%22The%20Odyssey%22)%3B%0A%0A%2F%2F%20Iterate%20over%20everything.%0Afor%20book%20in%20%26books%20%7B%0A%20%20%20%20println!(%22%7B%7D%22%2C%20book)%3B%0A%7D%0A%7D">Run</a></pre>
<p>The easiest way to use <code>HashSet</code> with a custom type is to derive
<a href="../../std/cmp/trait.Eq.html"><code>Eq</code></a> and <a href="../../std/hash/trait.Hash.html"><code>Hash</code></a>. We must also derive <a href="../../std/cmp/trait.PartialEq.html"><code>PartialEq</code></a>, this will in the
future be implied by <a href="../../std/cmp/trait.Eq.html"><code>Eq</code></a>.</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">HashSet</span>;
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Hash</span>, <span class="ident">Eq</span>, <span class="ident">PartialEq</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">Viking</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> {
<span class="ident">name</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">str</span>,
<span class="ident">power</span>: <span class="ident">usize</span>,
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">vikings</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="ident">vikings</span>.<span class="ident">insert</span>(<span class="ident">Viking</span> { <span class="ident">name</span>: <span class="string">"Einar"</span>, <span class="ident">power</span>: <span class="number">9</span> });
<span class="ident">vikings</span>.<span class="ident">insert</span>(<span class="ident">Viking</span> { <span class="ident">name</span>: <span class="string">"Einar"</span>, <span class="ident">power</span>: <span class="number">9</span> });
<span class="ident">vikings</span>.<span class="ident">insert</span>(<span class="ident">Viking</span> { <span class="ident">name</span>: <span class="string">"Olaf"</span>, <span class="ident">power</span>: <span class="number">4</span> });
<span class="ident">vikings</span>.<span class="ident">insert</span>(<span class="ident">Viking</span> { <span class="ident">name</span>: <span class="string">"Harald"</span>, <span class="ident">power</span>: <span class="number">8</span> });
<span class="comment">// Use derived implementation to print the vikings.</span>
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">vikings</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=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%23%5Bderive(Hash%2C%20Eq%2C%20PartialEq%2C%20Debug)%5D%0Astruct%20Viking%3C'a%3E%20%7B%0A%20%20%20%20name%3A%20%26'a%20str%2C%0A%20%20%20%20power%3A%20usize%2C%0A%7D%0A%0Alet%20mut%20vikings%20%3D%20HashSet%3A%3Anew()%3B%0A%0Avikings.insert(Viking%20%7B%20name%3A%20%22Einar%22%2C%20power%3A%209%20%7D)%3B%0Avikings.insert(Viking%20%7B%20name%3A%20%22Einar%22%2C%20power%3A%209%20%7D)%3B%0Avikings.insert(Viking%20%7B%20name%3A%20%22Olaf%22%2C%20power%3A%204%20%7D)%3B%0Avikings.insert(Viking%20%7B%20name%3A%20%22Harald%22%2C%20power%3A%208%20%7D)%3B%0A%0A%2F%2F%20Use%20derived%20implementation%20to%20print%20the%20vikings.%0Afor%20x%20in%20%26vikings%20%7B%0A%20%20%20%20println!(%22%7B%3A%3F%7D%22%2C%20x)%3B%0A%7D%0A%7D">Run</a></pre>
<p>A <code>HashSet</code> with fixed list of elements can be initialized from an array:</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">HashSet</span>;
<span class="kw">fn</span> <span class="ident">main</span>() {
<span class="kw">let</span> <span class="ident">viking_names</span>: <span class="ident">HashSet</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="string">"Einar"</span>, <span class="string">"Olaf"</span>, <span class="string">"Harald"</span> ].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="comment">// use the values stored in the set</span>
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=use%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Afn%20main()%20%7B%0A%20%20%20%20let%20viking_names%3A%20HashSet%3C%26str%3E%20%3D%0A%20%20%20%20%20%20%20%20%5B%20%22Einar%22%2C%20%22Olaf%22%2C%20%22Harald%22%20%5D.iter().cloned().collect()%3B%0A%20%20%20%20%2F%2F%20use%20the%20values%20stored%20in%20the%20set%0A%7D%0A">Run</a></pre>
</div><h2 id='methods'>Methods</h2><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a> + <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a>> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, <a class="struct" href="../../std/collections/hash_map/struct.RandomState.html" title="struct std::collections::hash_map::RandomState">RandomState</a>></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#125-156' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.new' class="method"><span id='new.v' class='invisible'><code>fn <a href='#method.new' class='fnname'>new</a>() -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, <a class="struct" href="../../std/collections/hash_map/struct.RandomState.html" title="struct std::collections::hash_map::RandomState">RandomState</a>></code></span></h4>
<div class='docblock'><p>Creates an empty HashSet.</p>
<h1 id='examples-1' class='section-header'><a href='#examples-1'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span>: <span class="ident">HashSet</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20mut%20set%3A%20HashSet%3Ci32%3E%20%3D%20HashSet%3A%3Anew()%3B%0A%7D">Run</a></pre>
</div><h4 id='method.with_capacity' class="method"><span id='with_capacity.v' class='invisible'><code>fn <a href='#method.with_capacity' class='fnname'>with_capacity</a>(capacity: <a class="primitive" href="../primitive.usize.html">usize</a>) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, <a class="struct" href="../../std/collections/hash_map/struct.RandomState.html" title="struct std::collections::hash_map::RandomState">RandomState</a>></code></span></h4>
<div class='docblock'><p>Creates an empty <code>HashSet</code> with the specified capacity.</p>
<p>The hash set will be able to hold at least <code>capacity</code> elements without
reallocating. If <code>capacity</code> is 0, the hash set will not allocate.</p>
<h1 id='examples-2' class='section-header'><a href='#examples-2'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span>: <span class="ident">HashSet</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">with_capacity</span>(<span class="number">10</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20mut%20set%3A%20HashSet%3Ci32%3E%20%3D%20HashSet%3A%3Awith_capacity(10)%3B%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, S> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#158-672' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.with_hasher' class="method"><span id='with_hasher.v' class='invisible'><code>fn <a href='#method.with_hasher' class='fnname'>with_hasher</a>(hasher: S) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code><div class='since' title='Stable since Rust version 1.7.0'>1.7.0</div></span></h4>
<div class='docblock'><p>Creates a new empty hash set which will use the given hasher to hash
keys.</p>
<p>The hash set is also created with the default initial capacity.</p>
<p>Warning: <code>hasher</code> is normally randomly generated, and
is designed to allow <code>HashSet</code>s to be resistant to attacks that
cause many collisions and very poor performance. Setting it
manually using this function can expose a DoS attack vector.</p>
<h1 id='examples-3' class='section-header'><a href='#examples-3'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">hash_map</span>::<span class="ident">RandomState</span>;
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">RandomState</span>::<span class="ident">new</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">with_hasher</span>(<span class="ident">s</span>);
<span class="ident">set</span>.<span class="ident">insert</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%3AHashSet%3B%0Ause%20std%3A%3Acollections%3A%3Ahash_map%3A%3ARandomState%3B%0A%0Alet%20s%20%3D%20RandomState%3A%3Anew()%3B%0Alet%20mut%20set%20%3D%20HashSet%3A%3Awith_hasher(s)%3B%0Aset.insert(2)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.with_capacity_and_hasher' class="method"><span id='with_capacity_and_hasher.v' class='invisible'><code>fn <a href='#method.with_capacity_and_hasher' class='fnname'>with_capacity_and_hasher</a>(capacity: <a class="primitive" href="../primitive.usize.html">usize</a>, hasher: S) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code><div class='since' title='Stable since Rust version 1.7.0'>1.7.0</div></span></h4>
<div class='docblock'><p>Creates an empty <code>HashSet</code> with with the specified capacity, using
<code>hasher</code> to hash the keys.</p>
<p>The hash set will be able to hold at least <code>capacity</code> elements without
reallocating. If <code>capacity</code> is 0, the hash set will not allocate.</p>
<p>Warning: <code>hasher</code> is normally randomly generated, and
is designed to allow <code>HashSet</code>s to be resistant to attacks that
cause many collisions and very poor performance. Setting it
manually using this function can expose a DoS attack vector.</p>
<h1 id='examples-4' class='section-header'><a href='#examples-4'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">hash_map</span>::<span class="ident">RandomState</span>;
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">RandomState</span>::<span class="ident">new</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">with_capacity_and_hasher</span>(<span class="number">10</span>, <span class="ident">s</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">1</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Ause%20std%3A%3Acollections%3A%3Ahash_map%3A%3ARandomState%3B%0A%0Alet%20s%20%3D%20RandomState%3A%3Anew()%3B%0Alet%20mut%20set%20%3D%20HashSet%3A%3Awith_capacity_and_hasher(10%2C%20s)%3B%0Aset.insert(1)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.hasher' class="method"><span id='hasher.v' class='invisible'><code>fn <a href='#method.hasher' class='fnname'>hasher</a>(&self) -> &S</code><div class='since' title='Stable since Rust version 1.9.0'>1.9.0</div></span></h4>
<div class='docblock'><p>Returns a reference to the set's <a href="../../std/hash/trait.BuildHasher.html"><code>BuildHasher</code></a>.</p>
</div><h4 id='method.capacity' class="method"><span id='capacity.v' class='invisible'><code>fn <a href='#method.capacity' class='fnname'>capacity</a>(&self) -> <a class="primitive" href="../primitive.usize.html">usize</a></code></span></h4>
<div class='docblock'><p>Returns the number of elements the set can hold without reallocating.</p>
<h1 id='examples-5' class='section-header'><a href='#examples-5'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">set</span>: <span class="ident">HashSet</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">with_capacity</span>(<span class="number">100</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">capacity</span>() <span class="op">>=</span> <span class="number">100</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20set%3A%20HashSet%3Ci32%3E%20%3D%20HashSet%3A%3Awith_capacity(100)%3B%0Aassert!(set.capacity()%20%3E%3D%20100)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.reserve' class="method"><span id='reserve.v' class='invisible'><code>fn <a href='#method.reserve' class='fnname'>reserve</a>(&mut self, additional: <a class="primitive" href="../primitive.usize.html">usize</a>)</code></span></h4>
<div class='docblock'><p>Reserves capacity for at least <code>additional</code> more elements to be inserted
in the <code>HashSet</code>. The collection may reserve more space to avoid
frequent reallocations.</p>
<h1 id='panics' class='section-header'><a href='#panics'>Panics</a></h1>
<p>Panics if the new allocation size overflows <code>usize</code>.</p>
<h1 id='examples-6' class='section-header'><a href='#examples-6'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span>: <span class="ident">HashSet</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="ident">set</span>.<span class="ident">reserve</span>(<span class="number">10</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20mut%20set%3A%20HashSet%3Ci32%3E%20%3D%20HashSet%3A%3Anew()%3B%0Aset.reserve(10)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.shrink_to_fit' class="method"><span id='shrink_to_fit.v' class='invisible'><code>fn <a href='#method.shrink_to_fit' class='fnname'>shrink_to_fit</a>(&mut self)</code></span></h4>
<div class='docblock'><p>Shrinks the capacity of the set as much as possible. It will drop
down as much as possible while maintaining the internal rules
and possibly leaving some space in accordance with the resize policy.</p>
<h1 id='examples-7' class='section-header'><a href='#examples-7'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">with_capacity</span>(<span class="number">100</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">1</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">2</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">capacity</span>() <span class="op">>=</span> <span class="number">100</span>);
<span class="ident">set</span>.<span class="ident">shrink_to_fit</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">capacity</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%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20mut%20set%20%3D%20HashSet%3A%3Awith_capacity(100)%3B%0Aset.insert(1)%3B%0Aset.insert(2)%3B%0Aassert!(set.capacity()%20%3E%3D%20100)%3B%0Aset.shrink_to_fit()%3B%0Aassert!(set.capacity()%20%3E%3D%202)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.iter' class="method"><span id='iter.v' class='invisible'><code>fn <a href='#method.iter' class='fnname'>iter</a>(&self) -> <a class="struct" href="../../std/collections/hash_set/struct.Iter.html" title="struct std::collections::hash_set::Iter">Iter</a><T></code></span></h4>
<div class='docblock'><p>An iterator visiting all elements in arbitrary order.
The iterator element type is <code>&'a T</code>.</p>
<h1 id='examples-8' class='section-header'><a href='#examples-8'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="string">"a"</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="string">"b"</span>);
<span class="comment">// Will print in an arbitrary order.</span>
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="ident">set</span>.<span class="ident">iter</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=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20mut%20set%20%3D%20HashSet%3A%3Anew()%3B%0Aset.insert(%22a%22)%3B%0Aset.insert(%22b%22)%3B%0A%0A%2F%2F%20Will%20print%20in%20an%20arbitrary%20order.%0Afor%20x%20in%20set.iter()%20%7B%0A%20%20%20%20println!(%22%7B%7D%22%2C%20x)%3B%0A%7D%0A%7D">Run</a></pre>
</div><h4 id='method.difference' class="method"><span id='difference.v' class='invisible'><code>fn <a href='#method.difference' class='fnname'>difference</a><'a>(&'a self, other: &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="struct" href="../../std/collections/hash_set/struct.Difference.html" title="struct std::collections::hash_set::Difference">Difference</a><'a, T, S></code></span></h4>
<div class='docblock'><p>Visits the values representing the difference,
i.e. the values that are in <code>self</code> but not in <code>other</code>.</p>
<h1 id='examples-9' class='section-header'><a href='#examples-9'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">4</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="comment">// Can be seen as `a - b`.</span>
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="ident">a</span>.<span class="ident">difference</span>(<span class="kw-2">&</span><span class="ident">b</span>) {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">x</span>); <span class="comment">// Print 1</span>
}
<span class="kw">let</span> <span class="ident">diff</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">difference</span>(<span class="kw-2">&</span><span class="ident">b</span>).<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">diff</span>, [<span class="number">1</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>());
<span class="comment">// Note that difference is not symmetric,</span>
<span class="comment">// and `b - a` means something else:</span>
<span class="kw">let</span> <span class="ident">diff</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="ident">b</span>.<span class="ident">difference</span>(<span class="kw-2">&</span><span class="ident">a</span>).<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">diff</span>, [<span class="number">4</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20%5B1%2C%202%2C%203%5D.iter().cloned().collect()%3B%0Alet%20b%3A%20HashSet%3C_%3E%20%3D%20%5B4%2C%202%2C%203%2C%204%5D.iter().cloned().collect()%3B%0A%0A%2F%2F%20Can%20be%20seen%20as%20%60a%20-%20b%60.%0Afor%20x%20in%20a.difference(%26b)%20%7B%0A%20%20%20%20println!(%22%7B%7D%22%2C%20x)%3B%20%2F%2F%20Print%201%0A%7D%0A%0Alet%20diff%3A%20HashSet%3C_%3E%20%3D%20a.difference(%26b).cloned().collect()%3B%0Aassert_eq!(diff%2C%20%5B1%5D.iter().cloned().collect())%3B%0A%0A%2F%2F%20Note%20that%20difference%20is%20not%20symmetric%2C%0A%2F%2F%20and%20%60b%20-%20a%60%20means%20something%20else%3A%0Alet%20diff%3A%20HashSet%3C_%3E%20%3D%20b.difference(%26a).cloned().collect()%3B%0Aassert_eq!(diff%2C%20%5B4%5D.iter().cloned().collect())%3B%0A%7D">Run</a></pre>
</div><h4 id='method.symmetric_difference' class="method"><span id='symmetric_difference.v' class='invisible'><code>fn <a href='#method.symmetric_difference' class='fnname'>symmetric_difference</a><'a>(<br> &'a self, <br> other: &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S><br>) -> <a class="struct" href="../../std/collections/hash_set/struct.SymmetricDifference.html" title="struct std::collections::hash_set::SymmetricDifference">SymmetricDifference</a><'a, T, S></code></span></h4>
<div class='docblock'><p>Visits the values representing the symmetric difference,
i.e. the values that are in <code>self</code> or in <code>other</code> but not in both.</p>
<h1 id='examples-10' class='section-header'><a href='#examples-10'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">4</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="comment">// Print 1, 4 in arbitrary order.</span>
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="ident">a</span>.<span class="ident">symmetric_difference</span>(<span class="kw-2">&</span><span class="ident">b</span>) {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">x</span>);
}
<span class="kw">let</span> <span class="ident">diff1</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">symmetric_difference</span>(<span class="kw-2">&</span><span class="ident">b</span>).<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">diff2</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="ident">b</span>.<span class="ident">symmetric_difference</span>(<span class="kw-2">&</span><span class="ident">a</span>).<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">diff1</span>, <span class="ident">diff2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">diff1</span>, [<span class="number">1</span>, <span class="number">4</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20%5B1%2C%202%2C%203%5D.iter().cloned().collect()%3B%0Alet%20b%3A%20HashSet%3C_%3E%20%3D%20%5B4%2C%202%2C%203%2C%204%5D.iter().cloned().collect()%3B%0A%0A%2F%2F%20Print%201%2C%204%20in%20arbitrary%20order.%0Afor%20x%20in%20a.symmetric_difference(%26b)%20%7B%0A%20%20%20%20println!(%22%7B%7D%22%2C%20x)%3B%0A%7D%0A%0Alet%20diff1%3A%20HashSet%3C_%3E%20%3D%20a.symmetric_difference(%26b).cloned().collect()%3B%0Alet%20diff2%3A%20HashSet%3C_%3E%20%3D%20b.symmetric_difference(%26a).cloned().collect()%3B%0A%0Aassert_eq!(diff1%2C%20diff2)%3B%0Aassert_eq!(diff1%2C%20%5B1%2C%204%5D.iter().cloned().collect())%3B%0A%7D">Run</a></pre>
</div><h4 id='method.intersection' class="method"><span id='intersection.v' class='invisible'><code>fn <a href='#method.intersection' class='fnname'>intersection</a><'a>(<br> &'a self, <br> other: &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S><br>) -> <a class="struct" href="../../std/collections/hash_set/struct.Intersection.html" title="struct std::collections::hash_set::Intersection">Intersection</a><'a, T, S></code></span></h4>
<div class='docblock'><p>Visits the values representing the intersection,
i.e. the values that are both in <code>self</code> and <code>other</code>.</p>
<h1 id='examples-11' class='section-header'><a href='#examples-11'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">4</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="comment">// Print 2, 3 in arbitrary order.</span>
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="ident">a</span>.<span class="ident">intersection</span>(<span class="kw-2">&</span><span class="ident">b</span>) {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">x</span>);
}
<span class="kw">let</span> <span class="ident">intersection</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">intersection</span>(<span class="kw-2">&</span><span class="ident">b</span>).<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">intersection</span>, [<span class="number">2</span>, <span class="number">3</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20%5B1%2C%202%2C%203%5D.iter().cloned().collect()%3B%0Alet%20b%3A%20HashSet%3C_%3E%20%3D%20%5B4%2C%202%2C%203%2C%204%5D.iter().cloned().collect()%3B%0A%0A%2F%2F%20Print%202%2C%203%20in%20arbitrary%20order.%0Afor%20x%20in%20a.intersection(%26b)%20%7B%0A%20%20%20%20println!(%22%7B%7D%22%2C%20x)%3B%0A%7D%0A%0Alet%20intersection%3A%20HashSet%3C_%3E%20%3D%20a.intersection(%26b).cloned().collect()%3B%0Aassert_eq!(intersection%2C%20%5B2%2C%203%5D.iter().cloned().collect())%3B%0A%7D">Run</a></pre>
</div><h4 id='method.union' class="method"><span id='union.v' class='invisible'><code>fn <a href='#method.union' class='fnname'>union</a><'a>(&'a self, other: &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="struct" href="../../std/collections/hash_set/struct.Union.html" title="struct std::collections::hash_set::Union">Union</a><'a, T, S></code></span></h4>
<div class='docblock'><p>Visits the values representing the union,
i.e. all the values in <code>self</code> or <code>other</code>, without duplicates.</p>
<h1 id='examples-12' class='section-header'><a href='#examples-12'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">4</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="comment">// Print 1, 2, 3, 4 in arbitrary order.</span>
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="ident">a</span>.<span class="ident">union</span>(<span class="kw-2">&</span><span class="ident">b</span>) {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">x</span>);
}
<span class="kw">let</span> <span class="ident">union</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">union</span>(<span class="kw-2">&</span><span class="ident">b</span>).<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">union</span>, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20%5B1%2C%202%2C%203%5D.iter().cloned().collect()%3B%0Alet%20b%3A%20HashSet%3C_%3E%20%3D%20%5B4%2C%202%2C%203%2C%204%5D.iter().cloned().collect()%3B%0A%0A%2F%2F%20Print%201%2C%202%2C%203%2C%204%20in%20arbitrary%20order.%0Afor%20x%20in%20a.union(%26b)%20%7B%0A%20%20%20%20println!(%22%7B%7D%22%2C%20x)%3B%0A%7D%0A%0Alet%20union%3A%20HashSet%3C_%3E%20%3D%20a.union(%26b).cloned().collect()%3B%0Aassert_eq!(union%2C%20%5B1%2C%202%2C%203%2C%204%5D.iter().cloned().collect())%3B%0A%7D">Run</a></pre>
</div><h4 id='method.len' class="method"><span id='len.v' class='invisible'><code>fn <a href='#method.len' class='fnname'>len</a>(&self) -> <a class="primitive" href="../primitive.usize.html">usize</a></code></span></h4>
<div class='docblock'><p>Returns the number of elements in the set.</p>
<h1 id='examples-13' class='section-header'><a href='#examples-13'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">v</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v</span>.<span class="ident">len</span>(), <span class="number">0</span>);
<span class="ident">v</span>.<span class="ident">insert</span>(<span class="number">1</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v</span>.<span class="ident">len</span>(), <span class="number">1</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20mut%20v%20%3D%20HashSet%3A%3Anew()%3B%0Aassert_eq!(v.len()%2C%200)%3B%0Av.insert(1)%3B%0Aassert_eq!(v.len()%2C%201)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.is_empty' class="method"><span id='is_empty.v' class='invisible'><code>fn <a href='#method.is_empty' class='fnname'>is_empty</a>(&self) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></h4>
<div class='docblock'><p>Returns true if the set contains no elements.</p>
<h1 id='examples-14' class='section-header'><a href='#examples-14'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">v</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">v</span>.<span class="ident">is_empty</span>());
<span class="ident">v</span>.<span class="ident">insert</span>(<span class="number">1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">v</span>.<span class="ident">is_empty</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20mut%20v%20%3D%20HashSet%3A%3Anew()%3B%0Aassert!(v.is_empty())%3B%0Av.insert(1)%3B%0Aassert!(!v.is_empty())%3B%0A%7D">Run</a></pre>
</div><h4 id='method.drain' class="method"><span id='drain.v' class='invisible'><code>fn <a href='#method.drain' class='fnname'>drain</a>(&mut self) -> <a class="struct" href="../../std/collections/hash_set/struct.Drain.html" title="struct std::collections::hash_set::Drain">Drain</a><T></code><div class='since' title='Stable since Rust version 1.6.0'>1.6.0</div></span></h4>
<div class='docblock'><p>Clears the set, returning all elements in an iterator.</p>
</div><h4 id='method.clear' class="method"><span id='clear.v' class='invisible'><code>fn <a href='#method.clear' class='fnname'>clear</a>(&mut self)</code></span></h4>
<div class='docblock'><p>Clears the set, removing all values.</p>
<h1 id='examples-15' class='section-header'><a href='#examples-15'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">v</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="ident">v</span>.<span class="ident">insert</span>(<span class="number">1</span>);
<span class="ident">v</span>.<span class="ident">clear</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">v</span>.<span class="ident">is_empty</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20mut%20v%20%3D%20HashSet%3A%3Anew()%3B%0Av.insert(1)%3B%0Av.clear()%3B%0Aassert!(v.is_empty())%3B%0A%7D">Run</a></pre>
</div><h4 id='method.contains' class="method"><span id='contains.v' class='invisible'><code>fn <a href='#method.contains' class='fnname'>contains</a><Q: ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>>(&self, value: &Q) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/borrow/trait.Borrow.html" title="trait std::borrow::Borrow">Borrow</a><Q>,<br> Q: <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a> + <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a>, </span></code></span></h4>
<div class='docblock'><p>Returns <code>true</code> if the set contains a value.</p>
<p>The value may be any borrowed form of the set's value type, but
<a href="../../std/hash/trait.Hash.html"><code>Hash</code></a> and <a href="../../std/cmp/trait.Eq.html"><code>Eq</code></a> on the borrowed form <em>must</em> match those for
the value type.</p>
<h1 id='examples-16' class='section-header'><a href='#examples-16'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">set</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</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">set</span>.<span class="ident">contains</span>(<span class="kw-2">&</span><span class="number">1</span>), <span class="bool-val">true</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">contains</span>(<span class="kw-2">&</span><span class="number">4</span>), <span class="bool-val">false</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20set%3A%20HashSet%3C_%3E%20%3D%20%5B1%2C%202%2C%203%5D.iter().cloned().collect()%3B%0Aassert_eq!(set.contains(%261)%2C%20true)%3B%0Aassert_eq!(set.contains(%264)%2C%20false)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.get' class="method"><span id='get.v' class='invisible'><code>fn <a href='#method.get' class='fnname'>get</a><Q: ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>>(&self, value: &Q) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><&T> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/borrow/trait.Borrow.html" title="trait std::borrow::Borrow">Borrow</a><Q>,<br> Q: <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a> + <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a>, </span></code><div class='since' title='Stable since Rust version 1.9.0'>1.9.0</div></span></h4>
<div class='docblock'><p>Returns a reference to the value in the set, if any, that is equal to the given value.</p>
<p>The value may be any borrowed form of the set's value type, but
<a href="../../std/hash/trait.Hash.html"><code>Hash</code></a> and <a href="../../std/cmp/trait.Eq.html"><code>Eq</code></a> on the borrowed form <em>must</em> match those for
the value type.</p>
</div><h4 id='method.is_disjoint' class="method"><span id='is_disjoint.v' class='invisible'><code>fn <a href='#method.is_disjoint' class='fnname'>is_disjoint</a>(&self, other: &<a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></h4>
<div class='docblock'><p>Returns <code>true</code> if <code>self</code> has no elements in common with <code>other</code>.
This is equivalent to checking for an empty intersection.</p>
<h1 id='examples-17' class='section-header'><a href='#examples-17'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">is_disjoint</span>(<span class="kw-2">&</span><span class="ident">b</span>), <span class="bool-val">true</span>);
<span class="ident">b</span>.<span class="ident">insert</span>(<span class="number">4</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">is_disjoint</span>(<span class="kw-2">&</span><span class="ident">b</span>), <span class="bool-val">true</span>);
<span class="ident">b</span>.<span class="ident">insert</span>(<span class="number">1</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">is_disjoint</span>(<span class="kw-2">&</span><span class="ident">b</span>), <span class="bool-val">false</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20%5B1%2C%202%2C%203%5D.iter().cloned().collect()%3B%0Alet%20mut%20b%20%3D%20HashSet%3A%3Anew()%3B%0A%0Aassert_eq!(a.is_disjoint(%26b)%2C%20true)%3B%0Ab.insert(4)%3B%0Aassert_eq!(a.is_disjoint(%26b)%2C%20true)%3B%0Ab.insert(1)%3B%0Aassert_eq!(a.is_disjoint(%26b)%2C%20false)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.is_subset' class="method"><span id='is_subset.v' class='invisible'><code>fn <a href='#method.is_subset' class='fnname'>is_subset</a>(&self, other: &<a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></h4>
<div class='docblock'><p>Returns <code>true</code> if the set is a subset of another,
i.e. <code>other</code> contains at least all the values in <code>self</code>.</p>
<h1 id='examples-18' class='section-header'><a href='#examples-18'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">sup</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">is_subset</span>(<span class="kw-2">&</span><span class="ident">sup</span>), <span class="bool-val">true</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">is_subset</span>(<span class="kw-2">&</span><span class="ident">sup</span>), <span class="bool-val">true</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">4</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">is_subset</span>(<span class="kw-2">&</span><span class="ident">sup</span>), <span class="bool-val">false</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20sup%3A%20HashSet%3C_%3E%20%3D%20%5B1%2C%202%2C%203%5D.iter().cloned().collect()%3B%0Alet%20mut%20set%20%3D%20HashSet%3A%3Anew()%3B%0A%0Aassert_eq!(set.is_subset(%26sup)%2C%20true)%3B%0Aset.insert(2)%3B%0Aassert_eq!(set.is_subset(%26sup)%2C%20true)%3B%0Aset.insert(4)%3B%0Aassert_eq!(set.is_subset(%26sup)%2C%20false)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.is_superset' class="method"><span id='is_superset.v' class='invisible'><code>fn <a href='#method.is_superset' class='fnname'>is_superset</a>(&self, other: &<a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></h4>
<div class='docblock'><p>Returns <code>true</code> if the set is a superset of another,
i.e. <code>self</code> contains at least all the values in <code>other</code>.</p>
<h1 id='examples-19' class='section-header'><a href='#examples-19'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">sub</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>].<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">is_superset</span>(<span class="kw-2">&</span><span class="ident">sub</span>), <span class="bool-val">false</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">0</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">1</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">is_superset</span>(<span class="kw-2">&</span><span class="ident">sub</span>), <span class="bool-val">false</span>);
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">is_superset</span>(<span class="kw-2">&</span><span class="ident">sub</span>), <span class="bool-val">true</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20sub%3A%20HashSet%3C_%3E%20%3D%20%5B1%2C%202%5D.iter().cloned().collect()%3B%0Alet%20mut%20set%20%3D%20HashSet%3A%3Anew()%3B%0A%0Aassert_eq!(set.is_superset(%26sub)%2C%20false)%3B%0A%0Aset.insert(0)%3B%0Aset.insert(1)%3B%0Aassert_eq!(set.is_superset(%26sub)%2C%20false)%3B%0A%0Aset.insert(2)%3B%0Aassert_eq!(set.is_superset(%26sub)%2C%20true)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.insert' class="method"><span id='insert.v' class='invisible'><code>fn <a href='#method.insert' class='fnname'>insert</a>(&mut self, value: T) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></h4>
<div class='docblock'><p>Adds a value to the set.</p>
<p>If the set did not have this value present, <code>true</code> is returned.</p>
<p>If the set did have this value present, <code>false</code> is returned.</p>
<h1 id='examples-20' class='section-header'><a href='#examples-20'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">2</span>), <span class="bool-val">true</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">2</span>), <span class="bool-val">false</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">len</span>(), <span class="number">1</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20mut%20set%20%3D%20HashSet%3A%3Anew()%3B%0A%0Aassert_eq!(set.insert(2)%2C%20true)%3B%0Aassert_eq!(set.insert(2)%2C%20false)%3B%0Aassert_eq!(set.len()%2C%201)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.replace' class="method"><span id='replace.v' class='invisible'><code>fn <a href='#method.replace' class='fnname'>replace</a>(&mut self, value: T) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><T></code><div class='since' title='Stable since Rust version 1.9.0'>1.9.0</div></span></h4>
<div class='docblock'><p>Adds a value to the set, replacing the existing value, if any, that is equal to the given
one. Returns the replaced value.</p>
</div><h4 id='method.remove' class="method"><span id='remove.v' class='invisible'><code>fn <a href='#method.remove' class='fnname'>remove</a><Q: ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>>(&mut self, value: &Q) -> <a class="primitive" href="../primitive.bool.html">bool</a> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/borrow/trait.Borrow.html" title="trait std::borrow::Borrow">Borrow</a><Q>,<br> Q: <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a> + <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a>, </span></code></span></h4>
<div class='docblock'><p>Removes a value from the set. Returns <code>true</code> if the value was
present in the set.</p>
<p>The value may be any borrowed form of the set's value type, but
<a href="../../std/hash/trait.Hash.html"><code>Hash</code></a> and <a href="../../std/cmp/trait.Eq.html"><code>Eq</code></a> on the borrowed form <em>must</em> match those for
the value type.</p>
<h1 id='examples-21' class='section-header'><a href='#examples-21'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">remove</span>(<span class="kw-2">&</span><span class="number">2</span>), <span class="bool-val">true</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">set</span>.<span class="ident">remove</span>(<span class="kw-2">&</span><span class="number">2</span>), <span class="bool-val">false</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20mut%20set%20%3D%20HashSet%3A%3Anew()%3B%0A%0Aset.insert(2)%3B%0Aassert_eq!(set.remove(%262)%2C%20true)%3B%0Aassert_eq!(set.remove(%262)%2C%20false)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.take' class="method"><span id='take.v' class='invisible'><code>fn <a href='#method.take' class='fnname'>take</a><Q: ?<a class="trait" href="../../std/marker/trait.Sized.html" title="trait std::marker::Sized">Sized</a>>(&mut self, value: &Q) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><T> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../std/borrow/trait.Borrow.html" title="trait std::borrow::Borrow">Borrow</a><Q>,<br> Q: <a class="trait" href="../../std/hash/trait.Hash.html" title="trait std::hash::Hash">Hash</a> + <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a>, </span></code><div class='since' title='Stable since Rust version 1.9.0'>1.9.0</div></span></h4>
<div class='docblock'><p>Removes and returns the value in the set, if any, that is equal to the given one.</p>
<p>The value may be any borrowed form of the set's value type, but
<a href="../../std/hash/trait.Hash.html"><code>Hash</code></a> and <a href="../../std/cmp/trait.Eq.html"><code>Eq</code></a> on the borrowed form <em>must</em> match those for
the value type.</p>
</div><h4 id='method.retain' class="method"><span id='retain.v' class='invisible'><code>fn <a href='#method.retain' class='fnname'>retain</a><F>(&mut self, f: 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>(&T) -> <a class="primitive" href="../primitive.bool.html">bool</a>, </span></code><div class='since' title='Stable since Rust version 1.18.0'>1.18.0</div></span></h4>
<div class='docblock'><p>Retains only the elements specified by the predicate.</p>
<p>In other words, remove all elements <code>e</code> such that <code>f(&e)</code> returns <code>false</code>.</p>
<h1 id='examples-22' class='section-header'><a href='#examples-22'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<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="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">set</span>: <span class="ident">HashSet</span><span class="op"><</span><span class="ident">isize</span><span class="op">></span> <span class="op">=</span> <span class="ident">xs</span>.<span class="ident">iter</span>().<span class="ident">cloned</span>().<span class="ident">collect</span>();
<span class="ident">set</span>.<span class="ident">retain</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">k</span><span class="op">|</span> <span class="ident">k</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">set</span>.<span class="ident">len</span>(), <span class="number">3</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20xs%20%3D%20%5B1%2C2%2C3%2C4%2C5%2C6%5D%3B%0Alet%20mut%20set%3A%20HashSet%3Cisize%3E%20%3D%20xs.iter().cloned().collect()%3B%0Aset.retain(%7C%26k%7C%20k%20%25%202%20%3D%3D%200)%3B%0Aassert_eq!(set.len()%2C%203)%3B%0A%7D">Run</a></pre>
</div></div><h2 id='implementations'>Trait Implementations</h2><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>, S: <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>> <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#119' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.clone' class="method"><span id='clone.v' class='invisible'><code>fn <a href='../../std/clone/trait.Clone.html#tymethod.clone' class='fnname'>clone</a>(&self) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>Returns a copy of the value. <a href="../../std/clone/trait.Clone.html#tymethod.clone">Read more</a></p>
</div><h4 id='method.clone_from' class="method"><span id='clone_from.v' class='invisible'><code>fn <a href='../../std/clone/trait.Clone.html#method.clone_from' class='fnname'>clone_from</a>(&mut self, source: &Self)</code></span></h4>
<div class='docblock'><p>Performs copy-assignment from <code>source</code>. <a href="../../std/clone/trait.Clone.html#method.clone_from">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, S> <a class="trait" href="../../std/cmp/trait.PartialEq.html" title="trait std::cmp::PartialEq">PartialEq</a> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#675-686' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.eq' class="method"><span id='eq.v' class='invisible'><code>fn <a href='../../std/cmp/trait.PartialEq.html#tymethod.eq' class='fnname'>eq</a>(&self, other: &<a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></h4>
<div class='docblock'><p>This method tests for <code>self</code> and <code>other</code> values to be equal, and is used by <code>==</code>. <a href="../../std/cmp/trait.PartialEq.html#tymethod.eq">Read more</a></p>
</div><h4 id='method.ne' class="method"><span id='ne.v' class='invisible'><code>fn <a href='../../std/cmp/trait.PartialEq.html#method.ne' class='fnname'>ne</a>(&self, other: &Rhs) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></h4>
<div class='docblock'><p>This method tests for <code>!=</code>.</p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, S> <a class="trait" href="../../std/cmp/trait.Eq.html" title="trait std::cmp::Eq">Eq</a> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#689-693' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'></div><h3 class='impl'><span class='in-band'><code>impl<T, S> <a class="trait" href="../../std/fmt/trait.Debug.html" title="trait std::fmt::Debug">Debug</a> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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> + <a class="trait" href="../../std/fmt/trait.Debug.html" title="trait std::fmt::Debug">Debug</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a>, </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#696-703' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><code>fn <a href='../../std/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, f: &mut <a class="struct" href="../../std/fmt/struct.Formatter.html" title="struct std::fmt::Formatter">Formatter</a>) -> <a class="type" href="../../std/fmt/type.Result.html" title="type std::fmt::Result">Result</a></code></span></h4>
<div class='docblock'><p>Formats the value using the given formatter.</p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, S> <a class="trait" href="../../std/iter/trait.FromIterator.html" title="trait std::iter::FromIterator">FromIterator</a><T> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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> + <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a>, </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#706-715' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.from_iter' class="method"><span id='from_iter.v' class='invisible'><code>fn <a href='../../std/iter/trait.FromIterator.html#tymethod.from_iter' class='fnname'>from_iter</a><I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a><Item = T>>(iter: I) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>Creates a value from an iterator. <a href="../../std/iter/trait.FromIterator.html#tymethod.from_iter">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, S> <a class="trait" href="../../std/iter/trait.Extend.html" title="trait std::iter::Extend">Extend</a><T> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#718-725' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.extend' class="method"><span id='extend.v' class='invisible'><code>fn <a href='../../std/iter/trait.Extend.html#tymethod.extend' class='fnname'>extend</a><I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a><Item = T>>(&mut self, iter: I)</code></span></h4>
<div class='docblock'><p>Extends a collection with the contents of an iterator. <a href="../../std/iter/trait.Extend.html#tymethod.extend">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'a, T, S> <a class="trait" href="../../std/iter/trait.Extend.html" title="trait std::iter::Extend">Extend</a><&'a T> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S> <span class="where fmt-newline">where<br> T: 'a + <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> + <a class="trait" href="../../std/marker/trait.Copy.html" title="trait std::marker::Copy">Copy</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a>, </span></code></span><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.4.0'>1.4.0</div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#728-735' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.extend-1' class="method"><span id='extend.v-1' class='invisible'><code>fn <a href='../../std/iter/trait.Extend.html#tymethod.extend' class='fnname'>extend</a><I: <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a><Item = &'a T>>(&mut self, iter: I)</code></span></h4>
<div class='docblock'><p>Extends a collection with the contents of an iterator. <a href="../../std/iter/trait.Extend.html#tymethod.extend">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, S> <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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> + <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a>, </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#738-746' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.default' class="method"><span id='default.v' class='invisible'><code>fn <a href='../../std/default/trait.Default.html#tymethod.default' class='fnname'>default</a>() -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>Creates an empty <code>HashSet<T, S></code> with the <code>Default</code> value for the hasher.</p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'a, 'b, T, S> <a class="trait" href="../../std/ops/trait.BitOr.html" title="trait std::ops::BitOr">BitOr</a><&'b <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>> for &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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> + <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a> + <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a>, </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#749-778' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Output' class="type"><span id='Output.t' class='invisible'><code>type <a href='../../std/ops/trait.BitOr.html#associatedtype.Output' class="type">Output</a> = <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>The resulting type after applying the <code>|</code> operator</p>
</div><h4 id='method.bitor' class="method"><span id='bitor.v' class='invisible'><code>fn <a href='../../std/ops/trait.BitOr.html#tymethod.bitor' class='fnname'>bitor</a>(self, rhs: &<a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>Returns the union of <code>self</code> and <code>rhs</code> as a new <code>HashSet<T, S></code>.</p>
<h1 id='examples-23' class='section-header'><a href='#examples-23'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</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="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>].<span class="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">set</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">a</span> <span class="op">|</span> <span class="kw-2">&</span><span class="ident">b</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="ident">expected</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">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">set</span> {
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">expected</span>.<span class="ident">contains</span>(<span class="ident">x</span>));
<span class="ident">i</span> <span class="op">+=</span> <span class="number">1</span>;
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">i</span>, <span class="ident">expected</span>.<span class="ident">len</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20vec!%5B1%2C%202%2C%203%5D.into_iter().collect()%3B%0Alet%20b%3A%20HashSet%3C_%3E%20%3D%20vec!%5B3%2C%204%2C%205%5D.into_iter().collect()%3B%0A%0Alet%20set%20%3D%20%26a%20%7C%20%26b%3B%0A%0Alet%20mut%20i%20%3D%200%3B%0Alet%20expected%20%3D%20%5B1%2C%202%2C%203%2C%204%2C%205%5D%3B%0Afor%20x%20in%20%26set%20%7B%0A%20%20%20%20assert!(expected.contains(x))%3B%0A%20%20%20%20i%20%2B%3D%201%3B%0A%7D%0Aassert_eq!(i%2C%20expected.len())%3B%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'a, 'b, T, S> <a class="trait" href="../../std/ops/trait.BitAnd.html" title="trait std::ops::BitAnd">BitAnd</a><&'b <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>> for &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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> + <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a> + <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a>, </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#781-810' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Output-1' class="type"><span id='Output.t-1' class='invisible'><code>type <a href='../../std/ops/trait.BitAnd.html#associatedtype.Output' class="type">Output</a> = <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>The resulting type after applying the <code>&</code> operator</p>
</div><h4 id='method.bitand' class="method"><span id='bitand.v' class='invisible'><code>fn <a href='../../std/ops/trait.BitAnd.html#tymethod.bitand' class='fnname'>bitand</a>(self, rhs: &<a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>Returns the intersection of <code>self</code> and <code>rhs</code> as a new <code>HashSet<T, S></code>.</p>
<h1 id='examples-24' class='section-header'><a href='#examples-24'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</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="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>].<span class="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">set</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">a</span> <span class="op">&</span> <span class="kw-2">&</span><span class="ident">b</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="ident">expected</span> <span class="op">=</span> [<span class="number">2</span>, <span class="number">3</span>];
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">set</span> {
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">expected</span>.<span class="ident">contains</span>(<span class="ident">x</span>));
<span class="ident">i</span> <span class="op">+=</span> <span class="number">1</span>;
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">i</span>, <span class="ident">expected</span>.<span class="ident">len</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20vec!%5B1%2C%202%2C%203%5D.into_iter().collect()%3B%0Alet%20b%3A%20HashSet%3C_%3E%20%3D%20vec!%5B2%2C%203%2C%204%5D.into_iter().collect()%3B%0A%0Alet%20set%20%3D%20%26a%20%26%20%26b%3B%0A%0Alet%20mut%20i%20%3D%200%3B%0Alet%20expected%20%3D%20%5B2%2C%203%5D%3B%0Afor%20x%20in%20%26set%20%7B%0A%20%20%20%20assert!(expected.contains(x))%3B%0A%20%20%20%20i%20%2B%3D%201%3B%0A%7D%0Aassert_eq!(i%2C%20expected.len())%3B%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'a, 'b, T, S> <a class="trait" href="../../std/ops/trait.BitXor.html" title="trait std::ops::BitXor">BitXor</a><&'b <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>> for &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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> + <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a> + <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a>, </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#813-842' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Output-2' class="type"><span id='Output.t-2' class='invisible'><code>type <a href='../../std/ops/trait.BitXor.html#associatedtype.Output' class="type">Output</a> = <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>The resulting type after applying the <code>^</code> operator</p>
</div><h4 id='method.bitxor' class="method"><span id='bitxor.v' class='invisible'><code>fn <a href='../../std/ops/trait.BitXor.html#tymethod.bitxor' class='fnname'>bitxor</a>(self, rhs: &<a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>Returns the symmetric difference of <code>self</code> and <code>rhs</code> as a new <code>HashSet<T, S></code>.</p>
<h1 id='examples-25' class='section-header'><a href='#examples-25'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</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="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>].<span class="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">set</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">a</span> <span class="op">^</span> <span class="kw-2">&</span><span class="ident">b</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="ident">expected</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">4</span>, <span class="number">5</span>];
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">set</span> {
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">expected</span>.<span class="ident">contains</span>(<span class="ident">x</span>));
<span class="ident">i</span> <span class="op">+=</span> <span class="number">1</span>;
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">i</span>, <span class="ident">expected</span>.<span class="ident">len</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20vec!%5B1%2C%202%2C%203%5D.into_iter().collect()%3B%0Alet%20b%3A%20HashSet%3C_%3E%20%3D%20vec!%5B3%2C%204%2C%205%5D.into_iter().collect()%3B%0A%0Alet%20set%20%3D%20%26a%20%5E%20%26b%3B%0A%0Alet%20mut%20i%20%3D%200%3B%0Alet%20expected%20%3D%20%5B1%2C%202%2C%204%2C%205%5D%3B%0Afor%20x%20in%20%26set%20%7B%0A%20%20%20%20assert!(expected.contains(x))%3B%0A%20%20%20%20i%20%2B%3D%201%3B%0A%7D%0Aassert_eq!(i%2C%20expected.len())%3B%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'a, 'b, T, S> <a class="trait" href="../../std/ops/trait.Sub.html" title="trait std::ops::Sub">Sub</a><&'b <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>> for &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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> + <a class="trait" href="../../std/clone/trait.Clone.html" title="trait std::clone::Clone">Clone</a>,<br> S: <a class="trait" href="../../std/hash/trait.BuildHasher.html" title="trait std::hash::BuildHasher">BuildHasher</a> + <a class="trait" href="../../std/default/trait.Default.html" title="trait std::default::Default">Default</a>, </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#845-874' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Output-3' class="type"><span id='Output.t-3' class='invisible'><code>type <a href='../../std/ops/trait.Sub.html#associatedtype.Output' class="type">Output</a> = <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>The resulting type after applying the <code>-</code> operator</p>
</div><h4 id='method.sub' class="method"><span id='sub.v' class='invisible'><code>fn <a href='../../std/ops/trait.Sub.html#tymethod.sub' class='fnname'>sub</a>(self, rhs: &<a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S>) -> <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</a><T, S></code></span></h4>
<div class='docblock'><p>Returns the difference of <code>self</code> and <code>rhs</code> as a new <code>HashSet<T, S></code>.</p>
<h1 id='examples-26' class='section-header'><a href='#examples-26'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="ident">a</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</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="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">HashSet</span><span class="op"><</span>_<span class="op">></span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>].<span class="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">set</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">a</span> <span class="op">-</span> <span class="kw-2">&</span><span class="ident">b</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="ident">expected</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>];
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">set</span> {
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">expected</span>.<span class="ident">contains</span>(<span class="ident">x</span>));
<span class="ident">i</span> <span class="op">+=</span> <span class="number">1</span>;
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">i</span>, <span class="ident">expected</span>.<span class="ident">len</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0A%0Alet%20a%3A%20HashSet%3C_%3E%20%3D%20vec!%5B1%2C%202%2C%203%5D.into_iter().collect()%3B%0Alet%20b%3A%20HashSet%3C_%3E%20%3D%20vec!%5B3%2C%204%2C%205%5D.into_iter().collect()%3B%0A%0Alet%20set%20%3D%20%26a%20-%20%26b%3B%0A%0Alet%20mut%20i%20%3D%200%3B%0Alet%20expected%20%3D%20%5B1%2C%202%5D%3B%0Afor%20x%20in%20%26set%20%7B%0A%20%20%20%20assert!(expected.contains(x))%3B%0A%20%20%20%20i%20%2B%3D%201%3B%0A%7D%0Aassert_eq!(i%2C%20expected.len())%3B%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'a, T, S> <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a> for &'a <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#967-977' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Item' class="type"><span id='Item.t' class='invisible'><code>type <a href='../../std/iter/trait.IntoIterator.html#associatedtype.Item' class="type">Item</a> = &'a T</code></span></h4>
<div class='docblock'><p>The type of the elements being iterated over.</p>
</div><h4 id='associatedtype.IntoIter' class="type"><span id='IntoIter.t' class='invisible'><code>type <a href='../../std/iter/trait.IntoIterator.html#associatedtype.IntoIter' class="type">IntoIter</a> = <a class="struct" href="../../std/collections/hash_set/struct.Iter.html" title="struct std::collections::hash_set::Iter">Iter</a><'a, T></code></span></h4>
<div class='docblock'><p>Which kind of iterator are we turning this into?</p>
</div><h4 id='method.into_iter' class="method"><span id='into_iter.v' class='invisible'><code>fn <a href='../../std/iter/trait.IntoIterator.html#tymethod.into_iter' class='fnname'>into_iter</a>(self) -> <a class="struct" href="../../std/collections/hash_set/struct.Iter.html" title="struct std::collections::hash_set::Iter">Iter</a><'a, T></code></span></h4>
<div class='docblock'><p>Creates an iterator from a value. <a href="../../std/iter/trait.IntoIterator.html#tymethod.into_iter">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, S> <a class="trait" href="../../std/iter/trait.IntoIterator.html" title="trait std::iter::IntoIterator">IntoIterator</a> for <a class="struct" href="../../std/collections/struct.HashSet.html" title="struct std::collections::HashSet">HashSet</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></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/collections/hash/set.rs.html#980-1010' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Item-1' class="type"><span id='Item.t-1' class='invisible'><code>type <a href='../../std/iter/trait.IntoIterator.html#associatedtype.Item' class="type">Item</a> = T</code></span></h4>
<div class='docblock'><p>The type of the elements being iterated over.</p>
</div><h4 id='associatedtype.IntoIter-1' class="type"><span id='IntoIter.t-1' class='invisible'><code>type <a href='../../std/iter/trait.IntoIterator.html#associatedtype.IntoIter' class="type">IntoIter</a> = <a class="struct" href="../../std/collections/hash_set/struct.IntoIter.html" title="struct std::collections::hash_set::IntoIter">IntoIter</a><T></code></span></h4>
<div class='docblock'><p>Which kind of iterator are we turning this into?</p>
</div><h4 id='method.into_iter-1' class="method"><span id='into_iter.v-1' class='invisible'><code>fn <a href='../../std/iter/trait.IntoIterator.html#tymethod.into_iter' class='fnname'>into_iter</a>(self) -> <a class="struct" href="../../std/collections/hash_set/struct.IntoIter.html" title="struct std::collections::hash_set::IntoIter">IntoIter</a><T></code></span></h4>
<div class='docblock'><p>Creates a consuming iterator, that is, one that moves each value out
of the set in arbitrary order. The set cannot be used after calling
this.</p>
<h1 id='examples-27' class='section-header'><a href='#examples-27'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">HashSet</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">set</span> <span class="op">=</span> <span class="ident">HashSet</span>::<span class="ident">new</span>();
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="string">"a"</span>.<span class="ident">to_string</span>());
<span class="ident">set</span>.<span class="ident">insert</span>(<span class="string">"b"</span>.<span class="ident">to_string</span>());
<span class="comment">// Not possible to collect to a Vec<String> with a regular `.iter()`.</span>
<span class="kw">let</span> <span class="ident">v</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">String</span><span class="op">></span> <span class="op">=</span> <span class="ident">set</span>.<span class="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="comment">// Will print in an arbitrary order.</span>
<span class="kw">for</span> <span class="ident">x</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">v</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=fn%20main()%20%7B%0Ause%20std%3A%3Acollections%3A%3AHashSet%3B%0Alet%20mut%20set%20%3D%20HashSet%3A%3Anew()%3B%0Aset.insert(%22a%22.to_string())%3B%0Aset.insert(%22b%22.to_string())%3B%0A%0A%2F%2F%20Not%20possible%20to%20collect%20to%20a%20Vec%3CString%3E%20with%20a%20regular%20%60.iter()%60.%0Alet%20v%3A%20Vec%3CString%3E%20%3D%20set.into_iter().collect()%3B%0A%0A%2F%2F%20Will%20print%20in%20an%20arbitrary%20order.%0Afor%20x%20in%20%26v%20%7B%0A%20%20%20%20println!(%22%7B%7D%22%2C%20x)%3B%0A%7D%0A%7D">Run</a></pre>
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