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<!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` fn in crate `nom`."><meta name="keywords" content="rust, rustlang, rust-lang, from_utf8"><title>nom::lib::std::str::from_utf8 - 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><noscript><link rel="stylesheet" href="../../../../noscript.css"></noscript><link rel="shortcut icon" href="../../../../favicon.ico"><style type="text/css">#crate-search{background-image:url("../../../../down-arrow.svg");}</style></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='../../../../nom/index.html'><div class='logo-container'><img src='../../../../rust-logo.png' alt='logo'></div></a><div class="sidebar-elems"><p class='location'><a href='../../../index.html'>nom</a>::<wbr><a href='../../index.html'>lib</a>::<wbr><a href='../index.html'>std</a>::<wbr><a href='index.html'>str</a></p><script>window.sidebarCurrent = {name: 'from_utf8', 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"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" disabled autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><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='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='https://doc.rust-lang.org/nightly/src/core/str/mod.rs.html#343-347' title='goto source code'>[src]</a></span><span class='in-band'>Function <a href='../../../index.html'>nom</a>::<wbr><a href='../../index.html'>lib</a>::<wbr><a href='../index.html'>std</a>::<wbr><a href='index.html'>str</a>::<wbr><a class="fn" href=''>from_utf8</a></span></h1><pre class='rust fn'>pub fn from_utf8(v: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">&[</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.slice.html">]</a>) -> <a class="enum" href="../../../../nom/lib/std/prelude/v1/v1/enum.Result.html" title="enum nom::lib::std::prelude::v1::v1::Result">Result</a><&<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.str.html">str</a>, <a class="struct" href="../../../../nom/lib/std/str/struct.Utf8Error.html" title="struct nom::lib::std::str::Utf8Error">Utf8Error</a>></pre><div class='docblock'><p>Converts a slice of bytes to a string slice.</p>
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<p>A string slice (<a href="../../std/primitive.str.html"><code>&str</code></a>) is made of bytes (<a href="../../std/primitive.u8.html"><code>u8</code></a>), and a byte slice
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(<a href="../../std/primitive.slice.html"><code>&[u8]</code></a>) is made of bytes, so this function converts between
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the two. Not all byte slices are valid string slices, however: <a href="../../std/primitive.str.html"><code>&str</code></a> requires
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that it is valid UTF-8. <code>from_utf8()</code> checks to ensure that the bytes are valid
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UTF-8, and then does the conversion.</p>
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<p>If you are sure that the byte slice is valid UTF-8, and you don't want to
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incur the overhead of the validity check, there is an unsafe version of
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this function, <a href="fn.from_utf8_unchecked.html"><code>from_utf8_unchecked</code></a>, which has the same
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behavior but skips the check.</p>
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<p>If you need a <code>String</code> instead of a <code>&str</code>, consider
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<a href="../../std/string/struct.String.html#method.from_utf8"><code>String::from_utf8</code></a>.</p>
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<p>Because you can stack-allocate a <code>[u8; N]</code>, and you can take a
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<a href="../../std/primitive.slice.html"><code>&[u8]</code></a> of it, this function is one way to have a
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stack-allocated string. There is an example of this in the
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examples section below.</p>
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<h1 id="errors" class="section-header"><a href="#errors">Errors</a></h1>
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<p>Returns <code>Err</code> if the slice is not UTF-8 with a description as to why the
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provided slice is not UTF-8.</p>
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<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
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<p>Basic usage:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">str</span>;
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<span class="comment">// some bytes, in a vector</span>
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<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>];
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<span class="comment">// We know these bytes are valid, so just use `unwrap()`.</span>
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<span class="kw">let</span> <span class="ident">sparkle_heart</span> <span class="op">=</span> <span class="ident">str</span>::<span class="ident">from_utf8</span>(<span class="kw-2">&</span><span class="ident">sparkle_heart</span>).<span class="ident">unwrap</span>();
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">"💖"</span>, <span class="ident">sparkle_heart</span>);</pre></div>
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<p>Incorrect bytes:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">str</span>;
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<span class="comment">// some invalid bytes, in a vector</span>
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<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">0</span>, <span class="number">159</span>, <span class="number">146</span>, <span class="number">150</span>];
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<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">str</span>::<span class="ident">from_utf8</span>(<span class="kw-2">&</span><span class="ident">sparkle_heart</span>).<span class="ident">is_err</span>());</pre></div>
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<p>See the docs for <a href="struct.Utf8Error.html"><code>Utf8Error</code></a> for more details on the kinds of
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errors that can be returned.</p>
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<p>A "stack allocated string":</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">str</span>;
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<span class="comment">// some bytes, in a stack-allocated array</span>
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<span class="kw">let</span> <span class="ident">sparkle_heart</span> <span class="op">=</span> [<span class="number">240</span>, <span class="number">159</span>, <span class="number">146</span>, <span class="number">150</span>];
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<span class="comment">// We know these bytes are valid, so just use `unwrap()`.</span>
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<span class="kw">let</span> <span class="ident">sparkle_heart</span> <span class="op">=</span> <span class="ident">str</span>::<span class="ident">from_utf8</span>(<span class="kw-2">&</span><span class="ident">sparkle_heart</span>).<span class="ident">unwrap</span>();
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">"💖"</span>, <span class="ident">sparkle_heart</span>);</pre></div>
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