<!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 `from_utf8_mut` fn in crate `alloc`."><meta name="keywords" content="rust, rustlang, rust-lang, from_utf8_mut"><title>alloc::str::from_utf8_mut - 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 fn"><!--[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='../../alloc/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a><div class="sidebar-elems"><p class='location'><a href='../index.html'>alloc</a>::<wbr><a href='index.html'>str</a></p><script>window.sidebarCurrent = {name: 'from_utf8_mut', ty: 'fn', 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'>Function <a href='../index.html'>alloc</a>::<wbr><a href='index.html'>str</a>::<wbr><a class="fn" href=''>from_utf8_mut</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.20.0'>1.20.0</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/str/mod.rs.html#374-377' title='goto source code'>[src]</a></span></h1><pre class='rust fn'>pub fn from_utf8_mut(v: &mut [u8]) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><&mut str, <a class="struct" href="../../alloc/str/struct.Utf8Error.html" title="struct alloc::str::Utf8Error">Utf8Error</a>></pre><div class='docblock'><p>Converts a mutable slice of bytes to a mutable string slice.</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">use</span> <span class="ident">std</span>::<span class="ident">str</span>;
<span class="comment">// "Hello, Rust!" as a mutable vector</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">hellorust</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">72</span>, <span class="number">101</span>, <span class="number">108</span>, <span class="number">108</span>, <span class="number">111</span>, <span class="number">44</span>, <span class="number">32</span>, <span class="number">82</span>, <span class="number">117</span>, <span class="number">115</span>, <span class="number">116</span>, <span class="number">33</span>];
<span class="comment">// As we know these bytes are valid, we can use `unwrap()`</span>
<span class="kw">let</span> <span class="ident">outstr</span> <span class="op">=</span> <span class="ident">str</span>::<span class="ident">from_utf8_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">hellorust</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">"Hello, Rust!"</span>, <span class="ident">outstr</span>);</pre>
<p>Incorrect bytes:</p>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">str</span>;
<span class="comment">// Some invalid bytes in a mutable vector</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">invalid</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">128</span>, <span class="number">223</span>];
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">str</span>::<span class="ident">from_utf8_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">invalid</span>).<span class="ident">is_err</span>());</pre>
<p>See the docs for <a href="struct.Utf8Error.html"><code>Utf8Error</code></a> for more details on the kinds of
errors that can be returned.</p>
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