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<p class='location'>Trait FromStr</p><div class="block items"><ul><li><a href="#associated-types">Associated Types</a></li><li><a href="#required-methods">Required Methods</a></li><li><a href="#implementors">Implementors</a></li></ul></div><p class='location'><a href='../index.html'>collections</a>::<wbr><a href='index.html'>str</a></p><script>window.sidebarCurrent = {name: 'FromStr', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<h1 class='fqn'><span class='in-band'>Trait <a href='../index.html'>collections</a>::<wbr><a href='index.html'>str</a>::<wbr><a class="trait" href=''>FromStr</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'>
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</span><a class='srclink' href='../../src/core/str/mod.rs.html#72-99' title='goto source code'>[src]</a></span></h1>
<pre class='rust trait'>pub trait FromStr {
type <a href='#associatedtype.Err' class="type">Err</a>;
fn <a href='#tymethod.from_str' class='fnname'>from_str</a>(s: &str) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><Self, Self::<a class="trait" href="../../collections/str/trait.FromStr.html" title="trait collections::str::FromStr">Err</a>>;
}</pre><div class='docblock'><p>A trait to abstract the idea of creating a new instance of a type from a
string.</p>
<p><code>FromStr</code>'s <a href="#tymethod.from_str"><code>from_str</code></a> method is often used implicitly, through
<a href="../../std/primitive.str.html"><code>str</code></a>'s <a href="../../std/primitive.str.html#method.parse"><code>parse</code></a> method. See <a href="../../std/primitive.str.html#method.parse"><code>parse</code></a>'s documentation for examples.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p>Basic implementation of <code>FromStr</code> on an example <code>Point</code> type:</p>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">str</span>::<span class="ident">FromStr</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">num</span>::<span class="ident">ParseIntError</span>;
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>, <span class="ident">PartialEq</span>)]</span>
<span class="kw">struct</span> <span class="ident">Point</span> {
<span class="ident">x</span>: <span class="ident">i32</span>,
<span class="ident">y</span>: <span class="ident">i32</span>
}
<span class="kw">impl</span> <span class="ident">FromStr</span> <span class="kw">for</span> <span class="ident">Point</span> {
<span class="kw">type</span> <span class="prelude-val">Err</span> <span class="op">=</span> <span class="ident">ParseIntError</span>;
<span class="kw">fn</span> <span class="ident">from_str</span>(<span class="ident">s</span>: <span class="kw-2">&</span><span class="ident">str</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="self">Self</span>, <span class="self">Self</span>::<span class="prelude-val">Err</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">coords</span>: <span class="ident">Vec</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">s</span>.<span class="ident">trim_matches</span>(<span class="op">|</span><span class="ident">p</span><span class="op">|</span> <span class="ident">p</span> <span class="op">==</span> <span class="string">'('</span> <span class="op">||</span> <span class="ident">p</span> <span class="op">==</span> <span class="string">')'</span> )
.<span class="ident">split</span>(<span class="string">","</span>)
.<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">x_fromstr</span> <span class="op">=</span> <span class="ident">coords</span>[<span class="number">0</span>].<span class="ident">parse</span>::<span class="op"><</span><span class="ident">i32</span><span class="op">></span>()<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">y_fromstr</span> <span class="op">=</span> <span class="ident">coords</span>[<span class="number">1</span>].<span class="ident">parse</span>::<span class="op"><</span><span class="ident">i32</span><span class="op">></span>()<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(<span class="ident">Point</span> { <span class="ident">x</span>: <span class="ident">x_fromstr</span>, <span class="ident">y</span>: <span class="ident">y_fromstr</span> })
}
}
<span class="kw">let</span> <span class="ident">p</span> <span class="op">=</span> <span class="ident">Point</span>::<span class="ident">from_str</span>(<span class="string">"(1,2)"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">p</span>.<span class="ident">unwrap</span>(), <span class="ident">Point</span>{ <span class="ident">x</span>: <span class="number">1</span>, <span class="ident">y</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%3Astr%3A%3AFromStr%3B%0Ause%20std%3A%3Anum%3A%3AParseIntError%3B%0A%0A%23%5Bderive(Debug%2C%20PartialEq)%5D%0Astruct%20Point%20%7B%0A%20%20%20%20x%3A%20i32%2C%0A%20%20%20%20y%3A%20i32%0A%7D%0A%0Aimpl%20FromStr%20for%20Point%20%7B%0A%20%20%20%20type%20Err%20%3D%20ParseIntError%3B%0A%0A%20%20%20%20fn%20from_str(s%3A%20%26str)%20-%3E%20Result%3CSelf%2C%20Self%3A%3AErr%3E%20%7B%0A%20%20%20%20%20%20%20%20let%20coords%3A%20Vec%3C%26str%3E%20%3D%20s.trim_matches(%7Cp%7C%20p%20%3D%3D%20'('%20%7C%7C%20p%20%3D%3D%20')'%20)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.split(%22%2C%22)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20.collect()%3B%0A%0A%20%20%20%20%20%20%20%20let%20x_fromstr%20%3D%20coords%5B0%5D.parse%3A%3A%3Ci32%3E()%3F%3B%0A%20%20%20%20%20%20%20%20let%20y_fromstr%20%3D%20coords%5B1%5D.parse%3A%3A%3Ci32%3E()%3F%3B%0A%0A%20%20%20%20%20%20%20%20Ok(Point%20%7B%20x%3A%20x_fromstr%2C%20y%3A%20y_fromstr%20%7D)%0A%20%20%20%20%7D%0A%7D%0A%0Alet%20p%20%3D%20Point%3A%3Afrom_str(%22(1%2C2)%22)%3B%0Aassert_eq!(p.unwrap()%2C%20Point%7B%20x%3A%201%2C%20y%3A%202%7D%20)%0A%7D">Run</a></pre>
</div>
<h2 id='associated-types'>Associated Types</h2>
<div class='methods'>
<h3 id='associatedtype.Err' class='method'><span id='Err.t' class='invisible'><code>type <a href='#associatedtype.Err' class="type">Err</a></code></span></h3><div class='docblock'><p>The associated error which can be returned from parsing.</p>
</div></div>
<h2 id='required-methods'>Required Methods</h2>
<div class='methods'>
<h3 id='tymethod.from_str' class='method'><span id='from_str.v' class='invisible'><code>fn <a href='#tymethod.from_str' class='fnname'>from_str</a>(s: &str) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><Self, Self::<a class="trait" href="../../collections/str/trait.FromStr.html" title="trait collections::str::FromStr">Err</a>></code></span></h3><div class='docblock'><p>Parses a string <code>s</code> to return a value of this type.</p>
<p>If parsing succeeds, return the value inside <code>Ok</code>, otherwise
when the string is ill-formatted return an error specific to the
inside <code>Err</code>. The error type is specific to implementation of the trait.</p>
<h1 id='examples-1' class='section-header'><a href='#examples-1'>Examples</a></h1>
<p>Basic usage with <a href="../../std/primitive.i32.html"><code>i32</code></a>, a type that implements <code>FromStr</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">str</span>::<span class="ident">FromStr</span>;
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="string">"5"</span>;
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">i32</span>::<span class="ident">from_str</span>(<span class="ident">s</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">5</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%3Astr%3A%3AFromStr%3B%0A%0Alet%20s%20%3D%20%225%22%3B%0Alet%20x%20%3D%20i32%3A%3Afrom_str(s).unwrap()%3B%0A%0Aassert_eq!(5%2C%20x)%3B%0A%7D">Run</a></pre>
</div></div>
<h2 id='implementors'>Implementors</h2>
<ul class='item-list' id='implementors-list'>
<li><code>impl FromStr for i64</code></li>
<li><code>impl FromStr for f64</code></li>
<li><code>impl FromStr for u16</code></li>
<li><code>impl FromStr for isize</code></li>
<li><code>impl FromStr for u8</code></li>
<li><code>impl FromStr for i8</code></li>
<li><code>impl FromStr for u128</code></li>
<li><code>impl FromStr for i128</code></li>
<li><code>impl FromStr for i32</code></li>
<li><code>impl FromStr for bool</code></li>
<li><code>impl FromStr for usize</code></li>
<li><code>impl FromStr for u64</code></li>
<li><code>impl FromStr for f32</code></li>
<li><code>impl FromStr for u32</code></li>
<li><code>impl FromStr for i16</code></li>
<li><code>impl FromStr for <a class="struct" href="../../collections/string/struct.String.html" title="struct collections::string::String">String</a></code></li>
</ul><script type="text/javascript" async
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