<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `string` mod in crate `std`."><meta name="keywords" content="rust, rustlang, rust-lang, string"><title>std::string - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"></head><body class="rustdoc mod"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../std/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a><p class='location'>Module string</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#structs">Structs</a></li><li><a href="#enums">Enums</a></li><li><a href="#traits">Traits</a></li></ul></div><p class='location'><a href='../index.html'>std</a></p><script>window.sidebarCurrent = {name: 'string', ty: 'mod', relpath: '../'};</script><script defer src="../sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='in-band'>Module <a href='../index.html'>std</a>::<wbr><a class="mod" href=''>string</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/alloc/lib.rs.html#184' title='goto source code'>[src]</a></span></h1><div class='docblock'><p>A UTF-8 encoded, growable string.</p>
<p>This module contains the <a href="struct.String.html"><code>String</code></a> type, a trait for converting
<a href="trait.ToString.html"><code>ToString</code></a>s, and several error types that may result from working with
<a href="struct.String.html"><code>String</code></a>s.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<p>There are multiple ways to create a new <a href="struct.String.html"><code>String</code></a> from a string literal:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="string">"Hello"</span>.<span class="ident">to_string</span>();
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">from</span>(<span class="string">"world"</span>);
<span class="kw">let</span> <span class="ident">s</span>: <span class="ident">String</span> <span class="op">=</span> <span class="string">"also this"</span>.<span class="ident">into</span>();<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Alet%20s%20%3D%20%22Hello%22.to_string()%3B%0A%0Alet%20s%20%3D%20String%3A%3Afrom(%22world%22)%3B%0Alet%20s%3A%20String%20%3D%20%22also%20this%22.into()%3B%0A%7D">Run</a></pre>
<p>You can create a new <a href="struct.String.html"><code>String</code></a> from an existing one by concatenating with
<code>+</code>:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="string">"Hello"</span>.<span class="ident">to_string</span>();
<span class="kw">let</span> <span class="ident">message</span> <span class="op">=</span> <span class="ident">s</span> <span class="op">+</span> <span class="string">" world!"</span>;<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Alet%20s%20%3D%20%22Hello%22.to_string()%3B%0A%0Alet%20message%20%3D%20s%20%2B%20%22%20world!%22%3B%0A%7D">Run</a></pre>
<p>If you have a vector of valid UTF-8 bytes, you can make a <a href="struct.String.html"><code>String</code></a> out of
it. You can do the reverse too.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">sparkle_heart</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">240</span>, <span class="number">159</span>, <span class="number">146</span>, <span class="number">150</span>];
<span class="comment">// We know these bytes are valid, so we'll use `unwrap()`.</span>
<span class="kw">let</span> <span class="ident">sparkle_heart</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">from_utf8</span>(<span class="ident">sparkle_heart</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">"💖"</span>, <span class="ident">sparkle_heart</span>);
<span class="kw">let</span> <span class="ident">bytes</span> <span class="op">=</span> <span class="ident">sparkle_heart</span>.<span class="ident">into_bytes</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">bytes</span>, [<span class="number">240</span>, <span class="number">159</span>, <span class="number">146</span>, <span class="number">150</span>]);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Alet%20sparkle_heart%20%3D%20vec!%5B240%2C%20159%2C%20146%2C%20150%5D%3B%0A%0A%2F%2F%20We%20know%20these%20bytes%20are%20valid%2C%20so%20we'll%20use%20%60unwrap()%60.%0Alet%20sparkle_heart%20%3D%20String%3A%3Afrom_utf8(sparkle_heart).unwrap()%3B%0A%0Aassert_eq!(%22%F0%9F%92%96%22%2C%20sparkle_heart)%3B%0A%0Alet%20bytes%20%3D%20sparkle_heart.into_bytes()%3B%0A%0Aassert_eq!(bytes%2C%20%5B240%2C%20159%2C%20146%2C%20150%5D)%3B%0A%7D">Run</a></pre>
</div><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
<table>
<tr class=' module-item'>
<td><a class="struct" href="struct.Drain.html"
title='struct std::string::Drain'>Drain</a></td>
<td class='docblock-short'>
<p>A draining iterator for <code>String</code>.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class="struct" href="struct.FromUtf16Error.html"
title='struct std::string::FromUtf16Error'>FromUtf16Error</a></td>
<td class='docblock-short'>
<p>A possible error value when converting a <code>String</code> from a UTF-16 byte slice.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class="struct" href="struct.FromUtf8Error.html"
title='struct std::string::FromUtf8Error'>FromUtf8Error</a></td>
<td class='docblock-short'>
<p>A possible error value when converting a <code>String</code> from a UTF-8 byte vector.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class="struct" href="struct.String.html"
title='struct std::string::String'>String</a></td>
<td class='docblock-short'>
<p>A UTF-8 encoded, growable string.</p>
</td>
</tr></table><h2 id='enums' class='section-header'><a href="#enums">Enums</a></h2>
<table>
<tr class=' module-item'>
<td><a class="enum" href="enum.ParseError.html"
title='enum std::string::ParseError'>ParseError</a></td>
<td class='docblock-short'>
<p>An error when parsing a <code>String</code>.</p>
</td>
</tr></table><h2 id='traits' class='section-header'><a href="#traits">Traits</a></h2>
<table>
<tr class=' module-item'>
<td><a class="trait" href="trait.ToString.html"
title='trait std::string::ToString'>ToString</a></td>
<td class='docblock-short'>
<p>A trait for converting a value to a <code>String</code>.</p>
</td>
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