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<p class='location'>Enum Result</p><div class="block items"><ul><li><a href="#variants">Variants</a></li><li><a href="#methods">Methods</a></li><li><a href="#implementations">Trait Implementations</a></li></ul></div><p class='location'><a href='../index.html'>core</a>::<wbr><a href='index.html'>result</a></p><script>window.sidebarCurrent = {name: 'Result', ty: 'enum', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<h1 class='fqn'><span class='in-band'>Enum <a href='../index.html'>core</a>::<wbr><a href='index.html'>result</a>::<wbr><a class="enum" href=''>Result</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/core/result.rs.html#253-261' title='goto source code'>[src]</a></span></h1>
<pre class='rust enum'><div class="docblock attributes">#[must_use]
</div>pub enum Result<T, E> {
Ok(T),
Err(E),
}</pre><div class='docblock'><p><code>Result</code> is a type that represents either success (<code>Ok</code>) or failure (<code>Err</code>).</p>
<p>See the <a href="index.html"><code>std::result</code></a> module documentation for details.</p>
</div><h2 id='variants' class='variants'>Variants</h2>
<span id='variant.Ok' class='variant'><span id='Ok.v' class='invisible'><code>Ok(T)</code></span></span><div class='docblock'><p>Contains the success value</p>
</div><span id='variant.Err' class='variant'><span id='Err.v' class='invisible'><code>Err(E)</code></span></span><div class='docblock'><p>Contains the error value</p>
</div><h2 id='methods'>Methods</h2><h3 class='impl'><span class='in-band'><code>impl<T, E> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#267-710' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.is_ok' class="method"><span id='is_ok.v' class='invisible'><code>fn <a href='#method.is_ok' class='fnname'>is_ok</a>(&self) -> bool</code></span></h4>
<div class='docblock'><p>Returns <code>true</code> if the result is <code>Ok</code>.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">i32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="op">-</span><span class="number">3</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">is_ok</span>(), <span class="bool-val">true</span>);
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">i32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"Some error message"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">is_ok</span>(), <span class="bool-val">false</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Ci32%2C%20%26str%3E%20%3D%20Ok(-3)%3B%0Aassert_eq!(x.is_ok()%2C%20true)%3B%0A%0Alet%20x%3A%20Result%3Ci32%2C%20%26str%3E%20%3D%20Err(%22Some%20error%20message%22)%3B%0Aassert_eq!(x.is_ok()%2C%20false)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.is_err' class="method"><span id='is_err.v' class='invisible'><code>fn <a href='#method.is_err' class='fnname'>is_err</a>(&self) -> bool</code></span></h4>
<div class='docblock'><p>Returns <code>true</code> if the result is <code>Err</code>.</p>
<h1 id='examples-1' class='section-header'><a href='#examples-1'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">i32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="op">-</span><span class="number">3</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">is_err</span>(), <span class="bool-val">false</span>);
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">i32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"Some error message"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">is_err</span>(), <span class="bool-val">true</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Ci32%2C%20%26str%3E%20%3D%20Ok(-3)%3B%0Aassert_eq!(x.is_err()%2C%20false)%3B%0A%0Alet%20x%3A%20Result%3Ci32%2C%20%26str%3E%20%3D%20Err(%22Some%20error%20message%22)%3B%0Aassert_eq!(x.is_err()%2C%20true)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.ok' class="method"><span id='ok.v' class='invisible'><code>fn <a href='#method.ok' class='fnname'>ok</a>(self) -> <a class="enum" href="../../core/option/enum.Option.html" title="enum core::option::Option">Option</a><T></code></span></h4>
<div class='docblock'><p>Converts from <code>Result<T, E></code> to <a href="../../std/option/enum.Option.html"><code>Option<T></code></a>.</p>
<p>Converts <code>self</code> into an <a href="../../std/option/enum.Option.html"><code>Option<T></code></a>, consuming <code>self</code>,
and discarding the error, if any.</p>
<h1 id='examples-2' class='section-header'><a href='#examples-2'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">ok</span>(), <span class="prelude-val">Some</span>(<span class="number">2</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"Nothing here"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">ok</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Aassert_eq!(x.ok()%2C%20Some(2))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22Nothing%20here%22)%3B%0Aassert_eq!(x.ok()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.err' class="method"><span id='err.v' class='invisible'><code>fn <a href='#method.err' class='fnname'>err</a>(self) -> <a class="enum" href="../../core/option/enum.Option.html" title="enum core::option::Option">Option</a><E></code></span></h4>
<div class='docblock'><p>Converts from <code>Result<T, E></code> to <a href="../../std/option/enum.Option.html"><code>Option<E></code></a>.</p>
<p>Converts <code>self</code> into an <a href="../../std/option/enum.Option.html"><code>Option<E></code></a>, consuming <code>self</code>,
and discarding the success value, if any.</p>
<h1 id='examples-3' class='section-header'><a href='#examples-3'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">err</span>(), <span class="prelude-val">None</span>);
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"Nothing here"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">err</span>(), <span class="prelude-val">Some</span>(<span class="string">"Nothing here"</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Aassert_eq!(x.err()%2C%20None)%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22Nothing%20here%22)%3B%0Aassert_eq!(x.err()%2C%20Some(%22Nothing%20here%22))%3B%0A%7D">Run</a></pre>
</div><h4 id='method.as_ref' class="method"><span id='as_ref.v' class='invisible'><code>fn <a href='#method.as_ref' class='fnname'>as_ref</a>(&self) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><&T, &E></code></span></h4>
<div class='docblock'><p>Converts from <code>Result<T, E></code> to <code>Result<&T, &E></code>.</p>
<p>Produces a new <code>Result</code>, containing a reference
into the original, leaving the original in place.</p>
<h1 id='examples-4' class='section-header'><a href='#examples-4'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">as_ref</span>(), <span class="prelude-val">Ok</span>(<span class="kw-2">&</span><span class="number">2</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"Error"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">as_ref</span>(), <span class="prelude-val">Err</span>(<span class="kw-2">&</span><span class="string">"Error"</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Aassert_eq!(x.as_ref()%2C%20Ok(%262))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22Error%22)%3B%0Aassert_eq!(x.as_ref()%2C%20Err(%26%22Error%22))%3B%0A%7D">Run</a></pre>
</div><h4 id='method.as_mut' class="method"><span id='as_mut.v' class='invisible'><code>fn <a href='#method.as_mut' class='fnname'>as_mut</a>(&mut self) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><&mut T, &mut E></code></span></h4>
<div class='docblock'><p>Converts from <code>Result<T, E></code> to <code>Result<&mut T, &mut E></code>.</p>
<h1 id='examples-5' class='section-header'><a href='#examples-5'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">fn</span> <span class="ident">mutate</span>(<span class="ident">r</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">i32</span>, <span class="ident">i32</span><span class="op">></span>) {
<span class="kw">match</span> <span class="ident">r</span>.<span class="ident">as_mut</span>() {
<span class="prelude-val">Ok</span>(<span class="ident">v</span>) <span class="op">=></span> <span class="kw-2">*</span><span class="ident">v</span> <span class="op">=</span> <span class="number">42</span>,
<span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=></span> <span class="kw-2">*</span><span class="ident">e</span> <span class="op">=</span> <span class="number">0</span>,
}
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">i32</span>, <span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="ident">mutate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">x</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">unwrap</span>(), <span class="number">42</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">i32</span>, <span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="number">13</span>);
<span class="ident">mutate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">x</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">unwrap_err</span>(), <span class="number">0</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Afn%20mutate(r%3A%20%26mut%20Result%3Ci32%2C%20i32%3E)%20%7B%0A%20%20%20%20match%20r.as_mut()%20%7B%0A%20%20%20%20%20%20%20%20Ok(v)%20%3D%3E%20*v%20%3D%2042%2C%0A%20%20%20%20%20%20%20%20Err(e)%20%3D%3E%20*e%20%3D%200%2C%0A%20%20%20%20%7D%0A%7D%0A%0Alet%20mut%20x%3A%20Result%3Ci32%2C%20i32%3E%20%3D%20Ok(2)%3B%0Amutate(%26mut%20x)%3B%0Aassert_eq!(x.unwrap()%2C%2042)%3B%0A%0Alet%20mut%20x%3A%20Result%3Ci32%2C%20i32%3E%20%3D%20Err(13)%3B%0Amutate(%26mut%20x)%3B%0Aassert_eq!(x.unwrap_err()%2C%200)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.map' class="method"><span id='map.v' class='invisible'><code>fn <a href='#method.map' class='fnname'>map</a><U, F: <a class="trait" href="../../core/ops/trait.FnOnce.html" title="trait core::ops::FnOnce">FnOnce</a>(T) -> U>(self, op: F) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E></code></span></h4>
<div class='docblock'><p>Maps a <code>Result<T, E></code> to <code>Result<U, E></code> by applying a function to a
contained <code>Ok</code> value, leaving an <code>Err</code> value untouched.</p>
<p>This function can be used to compose the results of two functions.</p>
<h1 id='examples-6' class='section-header'><a href='#examples-6'>Examples</a></h1>
<p>Print the numbers on each line of a string multiplied by two.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">line</span> <span class="op">=</span> <span class="string">"1\n2\n3\n4\n"</span>;
<span class="kw">for</span> <span class="ident">num</span> <span class="kw">in</span> <span class="ident">line</span>.<span class="ident">lines</span>() {
<span class="kw">match</span> <span class="ident">num</span>.<span class="ident">parse</span>::<span class="op"><</span><span class="ident">i32</span><span class="op">></span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">i</span><span class="op">|</span> <span class="ident">i</span> <span class="op">*</span> <span class="number">2</span>) {
<span class="prelude-val">Ok</span>(<span class="ident">n</span>) <span class="op">=></span> <span class="macro">println</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">n</span>),
<span class="prelude-val">Err</span>(..) <span class="op">=></span> {}
}
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20line%20%3D%20%221%5Cn2%5Cn3%5Cn4%5Cn%22%3B%0A%0Afor%20num%20in%20line.lines()%20%7B%0A%20%20%20%20match%20num.parse%3A%3A%3Ci32%3E().map(%7Ci%7C%20i%20*%202)%20%7B%0A%20%20%20%20%20%20%20%20Ok(n)%20%3D%3E%20println!(%22%7B%7D%22%2C%20n)%2C%0A%20%20%20%20%20%20%20%20Err(..)%20%3D%3E%20%7B%7D%0A%20%20%20%20%7D%0A%7D%0A%7D">Run</a></pre>
</div><h4 id='method.map_err' class="method"><span id='map_err.v' class='invisible'><code>fn <a href='#method.map_err' class='fnname'>map_err</a><F, O: <a class="trait" href="../../core/ops/trait.FnOnce.html" title="trait core::ops::FnOnce">FnOnce</a>(E) -> F>(self, op: O) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, F></code></span></h4>
<div class='docblock'><p>Maps a <code>Result<T, E></code> to <code>Result<T, F></code> by applying a function to a
contained <code>Err</code> value, leaving an <code>Ok</code> value untouched.</p>
<p>This function can be used to pass through a successful result while handling
an error.</p>
<h1 id='examples-7' class='section-header'><a href='#examples-7'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">fn</span> <span class="ident">stringify</span>(<span class="ident">x</span>: <span class="ident">u32</span>) <span class="op">-></span> <span class="ident">String</span> { <span class="macro">format</span><span class="macro">!</span>(<span class="string">"error code: {}"</span>, <span class="ident">x</span>) }
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">map_err</span>(<span class="ident">stringify</span>), <span class="prelude-val">Ok</span>(<span class="number">2</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="number">13</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">map_err</span>(<span class="ident">stringify</span>), <span class="prelude-val">Err</span>(<span class="string">"error code: 13"</span>.<span class="ident">to_string</span>()));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Afn%20stringify(x%3A%20u32)%20-%3E%20String%20%7B%20format!(%22error%20code%3A%20%7B%7D%22%2C%20x)%20%7D%0A%0Alet%20x%3A%20Result%3Cu32%2C%20u32%3E%20%3D%20Ok(2)%3B%0Aassert_eq!(x.map_err(stringify)%2C%20Ok(2))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20u32%3E%20%3D%20Err(13)%3B%0Aassert_eq!(x.map_err(stringify)%2C%20Err(%22error%20code%3A%2013%22.to_string()))%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="../../core/result/struct.Iter.html" title="struct core::result::Iter">Iter</a><T></code></span></h4>
<div class='docblock'><p>Returns an iterator over the possibly contained value.</p>
<p>The iterator yields one value if the result is <a href="enum.Result.html#variant.Ok"><code>Ok</code></a>, otherwise none.</p>
<h1 id='examples-8' class='section-header'><a href='#examples-8'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">7</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">iter</span>().<span class="ident">next</span>(), <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="number">7</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"nothing!"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">iter</span>().<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(7)%3B%0Aassert_eq!(x.iter().next()%2C%20Some(%267))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22nothing!%22)%3B%0Aassert_eq!(x.iter().next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.iter_mut' class="method"><span id='iter_mut.v' class='invisible'><code>fn <a href='#method.iter_mut' class='fnname'>iter_mut</a>(&mut self) -> <a class="struct" href="../../core/result/struct.IterMut.html" title="struct core::result::IterMut">IterMut</a><T></code></span></h4>
<div class='docblock'><p>Returns a mutable iterator over the possibly contained value.</p>
<p>The iterator yields one value if the result is <a href="enum.Result.html#variant.Ok"><code>Ok</code></a>, otherwise none.</p>
<h1 id='examples-9' class='section-header'><a href='#examples-9'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">7</span>);
<span class="kw">match</span> <span class="ident">x</span>.<span class="ident">iter_mut</span>().<span class="ident">next</span>() {
<span class="prelude-val">Some</span>(<span class="ident">v</span>) <span class="op">=></span> <span class="kw-2">*</span><span class="ident">v</span> <span class="op">=</span> <span class="number">40</span>,
<span class="prelude-val">None</span> <span class="op">=></span> {},
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>, <span class="prelude-val">Ok</span>(<span class="number">40</span>));
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"nothing!"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">iter_mut</span>().<span class="ident">next</span>(), <span class="prelude-val">None</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20mut%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(7)%3B%0Amatch%20x.iter_mut().next()%20%7B%0A%20%20%20%20Some(v)%20%3D%3E%20*v%20%3D%2040%2C%0A%20%20%20%20None%20%3D%3E%20%7B%7D%2C%0A%7D%0Aassert_eq!(x%2C%20Ok(40))%3B%0A%0Alet%20mut%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22nothing!%22)%3B%0Aassert_eq!(x.iter_mut().next()%2C%20None)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.and' class="method"><span id='and.v' class='invisible'><code>fn <a href='#method.and' class='fnname'>and</a><U>(self, res: <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E>) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E></code></span></h4>
<div class='docblock'><p>Returns <code>res</code> if the result is <code>Ok</code>, otherwise returns the <code>Err</code> value of <code>self</code>.</p>
<h1 id='examples-10' class='section-header'><a href='#examples-10'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="kw">let</span> <span class="ident">y</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"late error"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">and</span>(<span class="ident">y</span>), <span class="prelude-val">Err</span>(<span class="string">"late error"</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"early error"</span>);
<span class="kw">let</span> <span class="ident">y</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="string">"foo"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">and</span>(<span class="ident">y</span>), <span class="prelude-val">Err</span>(<span class="string">"early error"</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"not a 2"</span>);
<span class="kw">let</span> <span class="ident">y</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"late error"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">and</span>(<span class="ident">y</span>), <span class="prelude-val">Err</span>(<span class="string">"not a 2"</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="kw">let</span> <span class="ident">y</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="string">"different result type"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">and</span>(<span class="ident">y</span>), <span class="prelude-val">Ok</span>(<span class="string">"different result type"</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Alet%20y%3A%20Result%3C%26str%2C%20%26str%3E%20%3D%20Err(%22late%20error%22)%3B%0Aassert_eq!(x.and(y)%2C%20Err(%22late%20error%22))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22early%20error%22)%3B%0Alet%20y%3A%20Result%3C%26str%2C%20%26str%3E%20%3D%20Ok(%22foo%22)%3B%0Aassert_eq!(x.and(y)%2C%20Err(%22early%20error%22))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22not%20a%202%22)%3B%0Alet%20y%3A%20Result%3C%26str%2C%20%26str%3E%20%3D%20Err(%22late%20error%22)%3B%0Aassert_eq!(x.and(y)%2C%20Err(%22not%20a%202%22))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Alet%20y%3A%20Result%3C%26str%2C%20%26str%3E%20%3D%20Ok(%22different%20result%20type%22)%3B%0Aassert_eq!(x.and(y)%2C%20Ok(%22different%20result%20type%22))%3B%0A%7D">Run</a></pre>
</div><h4 id='method.and_then' class="method"><span id='and_then.v' class='invisible'><code>fn <a href='#method.and_then' class='fnname'>and_then</a><U, F: <a class="trait" href="../../core/ops/trait.FnOnce.html" title="trait core::ops::FnOnce">FnOnce</a>(T) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E>>(self, op: F) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E></code></span></h4>
<div class='docblock'><p>Calls <code>op</code> if the result is <code>Ok</code>, otherwise returns the <code>Err</code> value of <code>self</code>.</p>
<p>This function can be used for control flow based on <code>Result</code> values.</p>
<h1 id='examples-11' class='section-header'><a href='#examples-11'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">fn</span> <span class="ident">sq</span>(<span class="ident">x</span>: <span class="ident">u32</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="ident">u32</span><span class="op">></span> { <span class="prelude-val">Ok</span>(<span class="ident">x</span> <span class="op">*</span> <span class="ident">x</span>) }
<span class="kw">fn</span> <span class="ident">err</span>(<span class="ident">x</span>: <span class="ident">u32</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="ident">u32</span><span class="op">></span> { <span class="prelude-val">Err</span>(<span class="ident">x</span>) }
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Ok</span>(<span class="number">2</span>).<span class="ident">and_then</span>(<span class="ident">sq</span>).<span class="ident">and_then</span>(<span class="ident">sq</span>), <span class="prelude-val">Ok</span>(<span class="number">16</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Ok</span>(<span class="number">2</span>).<span class="ident">and_then</span>(<span class="ident">sq</span>).<span class="ident">and_then</span>(<span class="ident">err</span>), <span class="prelude-val">Err</span>(<span class="number">4</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Ok</span>(<span class="number">2</span>).<span class="ident">and_then</span>(<span class="ident">err</span>).<span class="ident">and_then</span>(<span class="ident">sq</span>), <span class="prelude-val">Err</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Err</span>(<span class="number">3</span>).<span class="ident">and_then</span>(<span class="ident">sq</span>).<span class="ident">and_then</span>(<span class="ident">sq</span>), <span class="prelude-val">Err</span>(<span class="number">3</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Afn%20sq(x%3A%20u32)%20-%3E%20Result%3Cu32%2C%20u32%3E%20%7B%20Ok(x%20*%20x)%20%7D%0Afn%20err(x%3A%20u32)%20-%3E%20Result%3Cu32%2C%20u32%3E%20%7B%20Err(x)%20%7D%0A%0Aassert_eq!(Ok(2).and_then(sq).and_then(sq)%2C%20Ok(16))%3B%0Aassert_eq!(Ok(2).and_then(sq).and_then(err)%2C%20Err(4))%3B%0Aassert_eq!(Ok(2).and_then(err).and_then(sq)%2C%20Err(2))%3B%0Aassert_eq!(Err(3).and_then(sq).and_then(sq)%2C%20Err(3))%3B%0A%7D">Run</a></pre>
</div><h4 id='method.or' class="method"><span id='or.v' class='invisible'><code>fn <a href='#method.or' class='fnname'>or</a><F>(self, res: <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, F>) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, F></code></span></h4>
<div class='docblock'><p>Returns <code>res</code> if the result is <code>Err</code>, otherwise returns the <code>Ok</code> value of <code>self</code>.</p>
<h1 id='examples-12' class='section-header'><a href='#examples-12'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="kw">let</span> <span class="ident">y</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"late error"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">or</span>(<span class="ident">y</span>), <span class="prelude-val">Ok</span>(<span class="number">2</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"early error"</span>);
<span class="kw">let</span> <span class="ident">y</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">or</span>(<span class="ident">y</span>), <span class="prelude-val">Ok</span>(<span class="number">2</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"not a 2"</span>);
<span class="kw">let</span> <span class="ident">y</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"late error"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">or</span>(<span class="ident">y</span>), <span class="prelude-val">Err</span>(<span class="string">"late error"</span>));
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="kw">let</span> <span class="ident">y</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">100</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">or</span>(<span class="ident">y</span>), <span class="prelude-val">Ok</span>(<span class="number">2</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Alet%20y%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22late%20error%22)%3B%0Aassert_eq!(x.or(y)%2C%20Ok(2))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22early%20error%22)%3B%0Alet%20y%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Aassert_eq!(x.or(y)%2C%20Ok(2))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22not%20a%202%22)%3B%0Alet%20y%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22late%20error%22)%3B%0Aassert_eq!(x.or(y)%2C%20Err(%22late%20error%22))%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Alet%20y%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(100)%3B%0Aassert_eq!(x.or(y)%2C%20Ok(2))%3B%0A%7D">Run</a></pre>
</div><h4 id='method.or_else' class="method"><span id='or_else.v' class='invisible'><code>fn <a href='#method.or_else' class='fnname'>or_else</a><F, O: <a class="trait" href="../../core/ops/trait.FnOnce.html" title="trait core::ops::FnOnce">FnOnce</a>(E) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, F>>(self, op: O) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, F></code></span></h4>
<div class='docblock'><p>Calls <code>op</code> if the result is <code>Err</code>, otherwise returns the <code>Ok</code> value of <code>self</code>.</p>
<p>This function can be used for control flow based on result values.</p>
<h1 id='examples-13' class='section-header'><a href='#examples-13'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">fn</span> <span class="ident">sq</span>(<span class="ident">x</span>: <span class="ident">u32</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="ident">u32</span><span class="op">></span> { <span class="prelude-val">Ok</span>(<span class="ident">x</span> <span class="op">*</span> <span class="ident">x</span>) }
<span class="kw">fn</span> <span class="ident">err</span>(<span class="ident">x</span>: <span class="ident">u32</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="ident">u32</span><span class="op">></span> { <span class="prelude-val">Err</span>(<span class="ident">x</span>) }
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Ok</span>(<span class="number">2</span>).<span class="ident">or_else</span>(<span class="ident">sq</span>).<span class="ident">or_else</span>(<span class="ident">sq</span>), <span class="prelude-val">Ok</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Ok</span>(<span class="number">2</span>).<span class="ident">or_else</span>(<span class="ident">err</span>).<span class="ident">or_else</span>(<span class="ident">sq</span>), <span class="prelude-val">Ok</span>(<span class="number">2</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Err</span>(<span class="number">3</span>).<span class="ident">or_else</span>(<span class="ident">sq</span>).<span class="ident">or_else</span>(<span class="ident">err</span>), <span class="prelude-val">Ok</span>(<span class="number">9</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Err</span>(<span class="number">3</span>).<span class="ident">or_else</span>(<span class="ident">err</span>).<span class="ident">or_else</span>(<span class="ident">err</span>), <span class="prelude-val">Err</span>(<span class="number">3</span>));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Afn%20sq(x%3A%20u32)%20-%3E%20Result%3Cu32%2C%20u32%3E%20%7B%20Ok(x%20*%20x)%20%7D%0Afn%20err(x%3A%20u32)%20-%3E%20Result%3Cu32%2C%20u32%3E%20%7B%20Err(x)%20%7D%0A%0Aassert_eq!(Ok(2).or_else(sq).or_else(sq)%2C%20Ok(2))%3B%0Aassert_eq!(Ok(2).or_else(err).or_else(sq)%2C%20Ok(2))%3B%0Aassert_eq!(Err(3).or_else(sq).or_else(err)%2C%20Ok(9))%3B%0Aassert_eq!(Err(3).or_else(err).or_else(err)%2C%20Err(3))%3B%0A%7D">Run</a></pre>
</div><h4 id='method.unwrap_or' class="method"><span id='unwrap_or.v' class='invisible'><code>fn <a href='#method.unwrap_or' class='fnname'>unwrap_or</a>(self, optb: T) -> T</code></span></h4>
<div class='docblock'><p>Unwraps a result, yielding the content of an <code>Ok</code>.
Else, it returns <code>optb</code>.</p>
<h1 id='examples-14' class='section-header'><a href='#examples-14'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">optb</span> <span class="op">=</span> <span class="number">2</span>;
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">9</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">unwrap_or</span>(<span class="ident">optb</span>), <span class="number">9</span>);
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"error"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">unwrap_or</span>(<span class="ident">optb</span>), <span class="ident">optb</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20optb%20%3D%202%3B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(9)%3B%0Aassert_eq!(x.unwrap_or(optb)%2C%209)%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22error%22)%3B%0Aassert_eq!(x.unwrap_or(optb)%2C%20optb)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.unwrap_or_else' class="method"><span id='unwrap_or_else.v' class='invisible'><code>fn <a href='#method.unwrap_or_else' class='fnname'>unwrap_or_else</a><F: <a class="trait" href="../../core/ops/trait.FnOnce.html" title="trait core::ops::FnOnce">FnOnce</a>(E) -> T>(self, op: F) -> T</code></span></h4>
<div class='docblock'><p>Unwraps a result, yielding the content of an <code>Ok</code>.
If the value is an <code>Err</code> then it calls <code>op</code> with its value.</p>
<h1 id='examples-15' class='section-header'><a href='#examples-15'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">fn</span> <span class="ident">count</span>(<span class="ident">x</span>: <span class="kw-2">&</span><span class="ident">str</span>) <span class="op">-></span> <span class="ident">usize</span> { <span class="ident">x</span>.<span class="ident">len</span>() }
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Ok</span>(<span class="number">2</span>).<span class="ident">unwrap_or_else</span>(<span class="ident">count</span>), <span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="prelude-val">Err</span>(<span class="string">"foo"</span>).<span class="ident">unwrap_or_else</span>(<span class="ident">count</span>), <span class="number">3</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Afn%20count(x%3A%20%26str)%20-%3E%20usize%20%7B%20x.len()%20%7D%0A%0Aassert_eq!(Ok(2).unwrap_or_else(count)%2C%202)%3B%0Aassert_eq!(Err(%22foo%22).unwrap_or_else(count)%2C%203)%3B%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, E: <a class="trait" href="../../core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a>> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#712-765' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.unwrap' class="method"><span id='unwrap.v' class='invisible'><code>fn <a href='#method.unwrap' class='fnname'>unwrap</a>(self) -> T</code></span></h4>
<div class='docblock'><p>Unwraps a result, yielding the content of an <code>Ok</code>.</p>
<h1 id='panics' class='section-header'><a href='#panics'>Panics</a></h1>
<p>Panics if the value is an <code>Err</code>, with a panic message provided by the
<code>Err</code>'s value.</p>
<h1 id='examples-16' class='section-header'><a href='#examples-16'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">unwrap</span>(), <span class="number">2</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Aassert_eq!(x.unwrap()%2C%202)%3B%0A%7D">Run</a></pre>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"emergency failure"</span>);
<span class="ident">x</span>.<span class="ident">unwrap</span>(); <span class="comment">// panics with `emergency failure`</span><a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22emergency%20failure%22)%3B%0Ax.unwrap()%3B%20%2F%2F%20panics%20with%20%60emergency%20failure%60%0A%7D">Run</a></pre>
</div><h4 id='method.expect' class="method"><span id='expect.v' class='invisible'><code>fn <a href='#method.expect' class='fnname'>expect</a>(self, msg: &str) -> T</code><div class='since' title='Stable since Rust version 1.4.0'>1.4.0</div></span></h4>
<div class='docblock'><p>Unwraps a result, yielding the content of an <code>Ok</code>.</p>
<h1 id='panics-1' class='section-header'><a href='#panics-1'>Panics</a></h1>
<p>Panics if the value is an <code>Err</code>, with a panic message including the
passed message, and the content of the <code>Err</code>.</p>
<h1 id='examples-17' class='section-header'><a href='#examples-17'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"emergency failure"</span>);
<span class="ident">x</span>.<span class="ident">expect</span>(<span class="string">"Testing expect"</span>); <span class="comment">// panics with `Testing expect: emergency failure`</span><a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22emergency%20failure%22)%3B%0Ax.expect(%22Testing%20expect%22)%3B%20%2F%2F%20panics%20with%20%60Testing%20expect%3A%20emergency%20failure%60%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a>, E> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#767-818' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.unwrap_err' class="method"><span id='unwrap_err.v' class='invisible'><code>fn <a href='#method.unwrap_err' class='fnname'>unwrap_err</a>(self) -> E</code></span></h4>
<div class='docblock'><p>Unwraps a result, yielding the content of an <code>Err</code>.</p>
<h1 id='panics-2' class='section-header'><a href='#panics-2'>Panics</a></h1>
<p>Panics if the value is an <code>Ok</code>, with a custom panic message provided
by the <code>Ok</code>'s value.</p>
<h1 id='examples-18' class='section-header'><a href='#examples-18'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">2</span>);
<span class="ident">x</span>.<span class="ident">unwrap_err</span>(); <span class="comment">// panics with `2`</span><a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(2)%3B%0Ax.unwrap_err()%3B%20%2F%2F%20panics%20with%20%602%60%0A%7D">Run</a></pre>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"emergency failure"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">x</span>.<span class="ident">unwrap_err</span>(), <span class="string">"emergency failure"</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22emergency%20failure%22)%3B%0Aassert_eq!(x.unwrap_err()%2C%20%22emergency%20failure%22)%3B%0A%7D">Run</a></pre>
</div><h4 id='method.expect_err' class="method"><span id='expect_err.v' class='invisible'><code>fn <a href='#method.expect_err' class='fnname'>expect_err</a>(self, msg: &str) -> E</code><div class='since' title='Stable since Rust version 1.17.0'>1.17.0</div></span></h4>
<div class='docblock'><p>Unwraps a result, yielding the content of an <code>Err</code>.</p>
<h1 id='panics-3' class='section-header'><a href='#panics-3'>Panics</a></h1>
<p>Panics if the value is an <code>Ok</code>, with a panic message including the
passed message, and the content of the <code>Ok</code>.</p>
<h1 id='examples-19' class='section-header'><a href='#examples-19'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">10</span>);
<span class="ident">x</span>.<span class="ident">expect_err</span>(<span class="string">"Testing expect_err"</span>); <span class="comment">// panics with `Testing expect_err: 10`</span><a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(10)%3B%0Ax.expect_err(%22Testing%20expect_err%22)%3B%20%2F%2F%20panics%20with%20%60Testing%20expect_err%3A%2010%60%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../core/default/trait.Default.html" title="trait core::default::Default">Default</a>, E> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#820-854' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.unwrap_or_default' class="method"><span id='unwrap_or_default.v' class='invisible'><code>fn <a href='#method.unwrap_or_default' class='fnname'>unwrap_or_default</a>(self) -> T</code><div class='since' title='Stable since Rust version 1.16.0'>1.16.0</div></span></h4>
<div class='docblock'><p>Returns the contained value or a default</p>
<p>Consumes the <code>self</code> argument then, if <code>Ok</code>, returns the contained
value, otherwise if <code>Err</code>, returns the default value for that
type.</p>
<h1 id='examples-20' class='section-header'><a href='#examples-20'>Examples</a></h1>
<p>Convert a string to an integer, turning poorly-formed strings
into 0 (the default value for integers). <a href="../../std/primitive.str.html#method.parse"><code>parse</code></a> converts
a string to any other type that implements <a href="../../std/str/trait.FromStr.html"><code>FromStr</code></a>, returning an
<code>Err</code> on error.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">good_year_from_input</span> <span class="op">=</span> <span class="string">"1909"</span>;
<span class="kw">let</span> <span class="ident">bad_year_from_input</span> <span class="op">=</span> <span class="string">"190blarg"</span>;
<span class="kw">let</span> <span class="ident">good_year</span> <span class="op">=</span> <span class="ident">good_year_from_input</span>.<span class="ident">parse</span>().<span class="ident">unwrap_or_default</span>();
<span class="kw">let</span> <span class="ident">bad_year</span> <span class="op">=</span> <span class="ident">bad_year_from_input</span>.<span class="ident">parse</span>().<span class="ident">unwrap_or_default</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">1909</span>, <span class="ident">good_year</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">0</span>, <span class="ident">bad_year</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20good_year_from_input%20%3D%20%221909%22%3B%0Alet%20bad_year_from_input%20%3D%20%22190blarg%22%3B%0Alet%20good_year%20%3D%20good_year_from_input.parse().unwrap_or_default()%3B%0Alet%20bad_year%20%3D%20bad_year_from_input.parse().unwrap_or_default()%3B%0A%0Aassert_eq!(1909%2C%20good_year)%3B%0Aassert_eq!(0%2C%20bad_year)%3B%0A%7D">Run</a></pre>
</div></div><h2 id='implementations'>Trait Implementations</h2><h3 class='impl'><span class='in-band'><code>impl<T, U, E> <a class="trait" href="../../core/iter/trait.Sum.html" title="trait core::iter::Sum">Sum</a><<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E>> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../core/iter/trait.Sum.html" title="trait core::iter::Sum">Sum</a><U>, </span></code></span><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.16.0'>1.16.0</div><a class='srclink' href='../../src/core/iter/traits.rs.html#798-806' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.sum' class="method"><span id='sum.v' class='invisible'><code>fn <a href='../../core/iter/trait.Sum.html#tymethod.sum' class='fnname'>sum</a><I>(iter: I) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../core/iter/trait.Iterator.html" title="trait core::iter::Iterator">Iterator</a><Item = <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E>>, </span></code></span></h4>
<div class='docblock'><p>Method which takes an iterator and generates <code>Self</code> from the elements by "summing up" the items. <a href="../../core/iter/trait.Sum.html#tymethod.sum">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, U, E> <a class="trait" href="../../core/iter/trait.Product.html" title="trait core::iter::Product">Product</a><<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E>> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E> <span class="where fmt-newline">where<br> T: <a class="trait" href="../../core/iter/trait.Product.html" title="trait core::iter::Product">Product</a><U>, </span></code></span><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.16.0'>1.16.0</div><a class='srclink' href='../../src/core/iter/traits.rs.html#809-817' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.product' class="method"><span id='product.v' class='invisible'><code>fn <a href='../../core/iter/trait.Product.html#tymethod.product' class='fnname'>product</a><I>(iter: I) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E> <span class="where fmt-newline">where<br> I: <a class="trait" href="../../core/iter/trait.Iterator.html" title="trait core::iter::Iterator">Iterator</a><Item = <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, E>>, </span></code></span></h4>
<div class='docblock'><p>Method which takes an iterator and generates <code>Self</code> from the elements by multiplying the items. <a href="../../core/iter/trait.Product.html#tymethod.product">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a>, E: <a class="trait" href="../../core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a>> <a class="trait" href="../../core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#250' 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='../../core/clone/trait.Clone.html#tymethod.clone' class='fnname'>clone</a>(&self) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span></h4>
<div class='docblock'><p>Returns a copy of the value. <a href="../../core/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='../../core/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="../../core/clone/trait.Clone.html#method.clone_from">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../core/marker/trait.Copy.html" title="trait core::marker::Copy">Copy</a>, E: <a class="trait" href="../../core/marker/trait.Copy.html" title="trait core::marker::Copy">Copy</a>> <a class="trait" href="../../core/marker/trait.Copy.html" title="trait core::marker::Copy">Copy</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#250' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'></div><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../core/cmp/trait.PartialEq.html" title="trait core::cmp::PartialEq">PartialEq</a>, E: <a class="trait" href="../../core/cmp/trait.PartialEq.html" title="trait core::cmp::PartialEq">PartialEq</a>> <a class="trait" href="../../core/cmp/trait.PartialEq.html" title="trait core::cmp::PartialEq">PartialEq</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#250' 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='../../core/cmp/trait.PartialEq.html#tymethod.eq' class='fnname'>eq</a>(&self, __arg_0: &<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E>) -> bool</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="../../core/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='../../core/cmp/trait.PartialEq.html#method.ne' class='fnname'>ne</a>(&self, __arg_0: &<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E>) -> bool</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: <a class="trait" href="../../core/cmp/trait.PartialOrd.html" title="trait core::cmp::PartialOrd">PartialOrd</a>, E: <a class="trait" href="../../core/cmp/trait.PartialOrd.html" title="trait core::cmp::PartialOrd">PartialOrd</a>> <a class="trait" href="../../core/cmp/trait.PartialOrd.html" title="trait core::cmp::PartialOrd">PartialOrd</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#250' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.partial_cmp' class="method"><span id='partial_cmp.v' class='invisible'><code>fn <a href='../../core/cmp/trait.PartialOrd.html#tymethod.partial_cmp' class='fnname'>partial_cmp</a>(&self, __arg_0: &<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E>) -> <a class="enum" href="../../core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="enum" href="../../core/cmp/enum.Ordering.html" title="enum core::cmp::Ordering">Ordering</a>></code></span></h4>
<div class='docblock'><p>This method returns an ordering between <code>self</code> and <code>other</code> values if one exists. <a href="../../core/cmp/trait.PartialOrd.html#tymethod.partial_cmp">Read more</a></p>
</div><h4 id='method.lt' class="method"><span id='lt.v' class='invisible'><code>fn <a href='../../core/cmp/trait.PartialOrd.html#method.lt' class='fnname'>lt</a>(&self, __arg_0: &<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E>) -> bool</code></span></h4>
<div class='docblock'><p>This method tests less than (for <code>self</code> and <code>other</code>) and is used by the <code><</code> operator. <a href="../../core/cmp/trait.PartialOrd.html#method.lt">Read more</a></p>
</div><h4 id='method.le' class="method"><span id='le.v' class='invisible'><code>fn <a href='../../core/cmp/trait.PartialOrd.html#method.le' class='fnname'>le</a>(&self, __arg_0: &<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E>) -> bool</code></span></h4>
<div class='docblock'><p>This method tests less than or equal to (for <code>self</code> and <code>other</code>) and is used by the <code><=</code> operator. <a href="../../core/cmp/trait.PartialOrd.html#method.le">Read more</a></p>
</div><h4 id='method.gt' class="method"><span id='gt.v' class='invisible'><code>fn <a href='../../core/cmp/trait.PartialOrd.html#method.gt' class='fnname'>gt</a>(&self, __arg_0: &<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E>) -> bool</code></span></h4>
<div class='docblock'><p>This method tests greater than (for <code>self</code> and <code>other</code>) and is used by the <code>></code> operator. <a href="../../core/cmp/trait.PartialOrd.html#method.gt">Read more</a></p>
</div><h4 id='method.ge' class="method"><span id='ge.v' class='invisible'><code>fn <a href='../../core/cmp/trait.PartialOrd.html#method.ge' class='fnname'>ge</a>(&self, __arg_0: &<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E>) -> bool</code></span></h4>
<div class='docblock'><p>This method tests greater than or equal to (for <code>self</code> and <code>other</code>) and is used by the <code>>=</code> operator. <a href="../../core/cmp/trait.PartialOrd.html#method.ge">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../core/cmp/trait.Eq.html" title="trait core::cmp::Eq">Eq</a>, E: <a class="trait" href="../../core/cmp/trait.Eq.html" title="trait core::cmp::Eq">Eq</a>> <a class="trait" href="../../core/cmp/trait.Eq.html" title="trait core::cmp::Eq">Eq</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#250' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'></div><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../core/cmp/trait.Ord.html" title="trait core::cmp::Ord">Ord</a>, E: <a class="trait" href="../../core/cmp/trait.Ord.html" title="trait core::cmp::Ord">Ord</a>> <a class="trait" href="../../core/cmp/trait.Ord.html" title="trait core::cmp::Ord">Ord</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#250' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.cmp' class="method"><span id='cmp.v' class='invisible'><code>fn <a href='../../core/cmp/trait.Ord.html#tymethod.cmp' class='fnname'>cmp</a>(&self, __arg_0: &<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E>) -> <a class="enum" href="../../core/cmp/enum.Ordering.html" title="enum core::cmp::Ordering">Ordering</a></code></span></h4>
<div class='docblock'><p>This method returns an <code>Ordering</code> between <code>self</code> and <code>other</code>. <a href="../../core/cmp/trait.Ord.html#tymethod.cmp">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="../../core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a>, E: <a class="trait" href="../../core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a>> <a class="trait" href="../../core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#250' 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='../../core/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, __arg_0: &mut <a class="struct" href="../../core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -> <a class="type" href="../../core/fmt/type.Result.html" title="type core::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: <a class="trait" href="../../core/hash/trait.Hash.html" title="trait core::hash::Hash">Hash</a>, E: <a class="trait" href="../../core/hash/trait.Hash.html" title="trait core::hash::Hash">Hash</a>> <a class="trait" href="../../core/hash/trait.Hash.html" title="trait core::hash::Hash">Hash</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#250' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.hash' class="method"><span id='hash.v' class='invisible'><code>fn <a href='../../core/hash/trait.Hash.html#tymethod.hash' class='fnname'>hash</a><__HTE: <a class="trait" href="../../core/hash/trait.Hasher.html" title="trait core::hash::Hasher">Hasher</a>>(&self, __arg_0: &mut __HTE)</code></span></h4>
<div class='docblock'><p>Feeds this value into the given [<code>Hasher</code>]. <a href="../../core/hash/trait.Hash.html#tymethod.hash">Read more</a></p>
</div><h4 id='method.hash_slice' class="method"><span id='hash_slice.v' class='invisible'><code>fn <a href='../../core/hash/trait.Hash.html#method.hash_slice' class='fnname'>hash_slice</a><H: <a class="trait" href="../../core/hash/trait.Hasher.html" title="trait core::hash::Hasher">Hasher</a>>(data: &[Self], state: &mut H) <span class="where fmt-newline">where<br> Self: <a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></code><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div></span></h4>
<div class='docblock'><p>Feeds a slice of this type into the given [<code>Hasher</code>]. <a href="../../core/hash/trait.Hash.html#method.hash_slice">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, E> <a class="trait" href="../../core/iter/trait.IntoIterator.html" title="trait core::iter::IntoIterator">IntoIterator</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#868-895' 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='../../core/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' class="type"><span id='IntoIter.t' class='invisible'><code>type <a href='../../core/iter/trait.IntoIterator.html#associatedtype.IntoIter' class="type">IntoIter</a> = <a class="struct" href="../../core/result/struct.IntoIter.html" title="struct core::result::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' class="method"><span id='into_iter.v' class='invisible'><code>fn <a href='../../core/iter/trait.IntoIterator.html#tymethod.into_iter' class='fnname'>into_iter</a>(self) -> <a class="struct" href="../../core/result/struct.IntoIter.html" title="struct core::result::IntoIter">IntoIter</a><T></code></span></h4>
<div class='docblock'><p>Returns a consuming iterator over the possibly contained value.</p>
<p>The iterator yields one value if the result is <a href="enum.Result.html#variant.Ok"><code>Ok</code></a>, otherwise none.</p>
<h1 id='examples-21' class='section-header'><a href='#examples-21'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Ok</span>(<span class="number">5</span>);
<span class="kw">let</span> <span class="ident">v</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v</span>, [<span class="number">5</span>]);
<span class="kw">let</span> <span class="ident">x</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u32</span>, <span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="prelude-val">Err</span>(<span class="string">"nothing!"</span>);
<span class="kw">let</span> <span class="ident">v</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">into_iter</span>().<span class="ident">collect</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">v</span>, []);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Ok(5)%3B%0Alet%20v%3A%20Vec%3Cu32%3E%20%3D%20x.into_iter().collect()%3B%0Aassert_eq!(v%2C%20%5B5%5D)%3B%0A%0Alet%20x%3A%20Result%3Cu32%2C%20%26str%3E%20%3D%20Err(%22nothing!%22)%3B%0Alet%20v%3A%20Vec%3Cu32%3E%20%3D%20x.into_iter().collect()%3B%0Aassert_eq!(v%2C%20%5B%5D)%3B%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'a, T, E> <a class="trait" href="../../core/iter/trait.IntoIterator.html" title="trait core::iter::IntoIterator">IntoIterator</a> for &'a <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></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/core/result.rs.html#898-905' 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='../../core/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-1' class="type"><span id='IntoIter.t-1' class='invisible'><code>type <a href='../../core/iter/trait.IntoIterator.html#associatedtype.IntoIter' class="type">IntoIter</a> = <a class="struct" href="../../core/result/struct.Iter.html" title="struct core::result::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-1' class="method"><span id='into_iter.v-1' class='invisible'><code>fn <a href='../../core/iter/trait.IntoIterator.html#tymethod.into_iter' class='fnname'>into_iter</a>(self) -> <a class="struct" href="../../core/result/struct.Iter.html" title="struct core::result::Iter">Iter</a><'a, T></code></span></h4>
<div class='docblock'><p>Creates an iterator from a value. <a href="../../core/iter/trait.IntoIterator.html#tymethod.into_iter">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'a, T, E> <a class="trait" href="../../core/iter/trait.IntoIterator.html" title="trait core::iter::IntoIterator">IntoIterator</a> for &'a mut <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></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/core/result.rs.html#908-915' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Item-2' class="type"><span id='Item.t-2' class='invisible'><code>type <a href='../../core/iter/trait.IntoIterator.html#associatedtype.Item' class="type">Item</a> = &'a mut T</code></span></h4>
<div class='docblock'><p>The type of the elements being iterated over.</p>
</div><h4 id='associatedtype.IntoIter-2' class="type"><span id='IntoIter.t-2' class='invisible'><code>type <a href='../../core/iter/trait.IntoIterator.html#associatedtype.IntoIter' class="type">IntoIter</a> = <a class="struct" href="../../core/result/struct.IterMut.html" title="struct core::result::IterMut">IterMut</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-2' class="method"><span id='into_iter.v-2' class='invisible'><code>fn <a href='../../core/iter/trait.IntoIterator.html#tymethod.into_iter' class='fnname'>into_iter</a>(self) -> <a class="struct" href="../../core/result/struct.IterMut.html" title="struct core::result::IterMut">IterMut</a><'a, T></code></span></h4>
<div class='docblock'><p>Creates an iterator from a value. <a href="../../core/iter/trait.IntoIterator.html#tymethod.into_iter">Read more</a></p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<A, E, V: <a class="trait" href="../../core/iter/trait.FromIterator.html" title="trait core::iter::FromIterator">FromIterator</a><A>> <a class="trait" href="../../core/iter/trait.FromIterator.html" title="trait core::iter::FromIterator">FromIterator</a><<a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><A, E>> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><V, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#1054-1111' 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='../../core/iter/trait.FromIterator.html#tymethod.from_iter' class='fnname'>from_iter</a><I: <a class="trait" href="../../core/iter/trait.IntoIterator.html" title="trait core::iter::IntoIterator">IntoIterator</a><Item = <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><A, E>>>(iter: I) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><V, E></code></span></h4>
<div class='docblock'><p>Takes each element in the <code>Iterator</code>: if it is an <code>Err</code>, no further
elements are taken, and the <code>Err</code> is returned. Should no <code>Err</code> occur, a
container with the values of each <code>Result</code> is returned.</p>
<p>Here is an example which increments every integer in a vector,
checking for overflow:</p>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">u32</span>;
<span class="kw">let</span> <span class="ident">v</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="kw">let</span> <span class="ident">res</span>: <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span>, <span class="kw-2">&</span><span class="lifetime">'static</span> <span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">v</span>.<span class="ident">iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span>: <span class="kw-2">&</span><span class="ident">u32</span><span class="op">|</span>
<span class="kw">if</span> <span class="ident">x</span> <span class="op">==</span> <span class="ident">u32</span>::<span class="ident">MAX</span> { <span class="prelude-val">Err</span>(<span class="string">"Overflow!"</span>) }
<span class="kw">else</span> { <span class="prelude-val">Ok</span>(<span class="ident">x</span> <span class="op">+</span> <span class="number">1</span>) }
).<span class="ident">collect</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">res</span> <span class="op">==</span> <span class="prelude-val">Ok</span>(<span class="macro">vec</span><span class="macro">!</span>[<span class="number">2</span>, <span class="number">3</span>]));<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Au32%3B%0A%0Alet%20v%20%3D%20vec!%5B1%2C%202%5D%3B%0Alet%20res%3A%20Result%3CVec%3Cu32%3E%2C%20%26'static%20str%3E%20%3D%20v.iter().map(%7C%26x%3A%20%26u32%7C%0A%20%20%20%20if%20x%20%3D%3D%20u32%3A%3AMAX%20%7B%20Err(%22Overflow!%22)%20%7D%0A%20%20%20%20else%20%7B%20Ok(x%20%2B%201)%20%7D%0A).collect()%3B%0Aassert!(res%20%3D%3D%20Ok(vec!%5B2%2C%203%5D))%3B%0A%7D">Run</a></pre>
</div></div><h3 class='impl'><span class='in-band'><code>impl<T, E> <a class="trait" href="../../core/ops/trait.Try.html" title="trait core::ops::Try">Try</a> for <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, E></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/result.rs.html#1114-1129' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Ok' class="type"><span id='Ok.t' class='invisible'><code>type <a href='../../core/ops/trait.Try.html#associatedtype.Ok' class="type">Ok</a> = T</code></span></h4>
<div class='stability'><div class='stab unstable'><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>try_trait </code><a href="https://github.com/rust-lang/rust/issues/42327">#42327</a>)</div></div><div class='docblock'><p>The type of this value when viewed as successful.</p>
</div><h4 id='associatedtype.Error' class="type"><span id='Error.t' class='invisible'><code>type <a href='../../core/ops/trait.Try.html#associatedtype.Error' class="type">Error</a> = E</code></span></h4>
<div class='stability'><div class='stab unstable'><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>try_trait </code><a href="https://github.com/rust-lang/rust/issues/42327">#42327</a>)</div></div><div class='docblock'><p>The type of this value when viewed as failed.</p>
</div><h4 id='method.into_result' class="method"><span id='into_result.v' class='invisible'><code>fn <a href='../../core/ops/trait.Try.html#tymethod.into_result' class='fnname'>into_result</a>(self) -> Self</code></span></h4>
<div class='stability'><div class='stab unstable'><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>try_trait </code><a href="https://github.com/rust-lang/rust/issues/42327">#42327</a>)</div></div><div class='docblock'><p>Applies the "?" operator. A return of <code>Ok(t)</code> means that the execution should continue normally, and the result of <code>?</code> is the value <code>t</code>. A return of <code>Err(e)</code> means that execution should branch to the innermost enclosing <code>catch</code>, or return from the function. <a href="../../core/ops/trait.Try.html#tymethod.into_result">Read more</a></p>
</div><h4 id='method.from_ok' class="method"><span id='from_ok.v' class='invisible'><code>fn <a href='../../core/ops/trait.Try.html#tymethod.from_ok' class='fnname'>from_ok</a>(v: T) -> Self</code></span></h4>
<div class='stability'><div class='stab unstable'><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>try_trait </code><a href="https://github.com/rust-lang/rust/issues/42327">#42327</a>)</div></div><div class='docblock'><p>Wrap an OK value to construct the composite result. For example, <code>Result::Ok(x)</code> and <code>Result::from_ok(x)</code> are equivalent. <a href="../../core/ops/trait.Try.html#tymethod.from_ok">Read more</a></p>
</div><h4 id='method.from_error' class="method"><span id='from_error.v' class='invisible'><code>fn <a href='../../core/ops/trait.Try.html#tymethod.from_error' class='fnname'>from_error</a>(v: E) -> Self</code></span></h4>
<div class='stability'><div class='stab unstable'><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>try_trait </code><a href="https://github.com/rust-lang/rust/issues/42327">#42327</a>)</div></div><div class='docblock'><p>Wrap an error value to construct the composite result. For example, <code>Result::Err(x)</code> and <code>Result::from_error(x)</code> are equivalent. <a href="../../core/ops/trait.Try.html#tymethod.from_error">Read more</a></p>
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