16 lines
5.8 KiB
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16 lines
5.8 KiB
HTML
<!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 `memrchr` fn in crate `memchr`."><meta name="keywords" content="rust, rustlang, rust-lang, memrchr"><title>memchr::memrchr - 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='../memchr/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'>memchr</a></p><script>window.sidebarCurrent = {name: 'memrchr', 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"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" 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 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/memchr/lib.rs.html#233-263' title='goto source code'>[src]</a></span><span class='in-band'>Function <a href='index.html'>memchr</a>::<wbr><a class="fn" href=''>memrchr</a></span></h1><pre class='rust fn'>pub fn memrchr(needle: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>, haystack: <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="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>></pre><div class='docblock'><p>Search for the last occurrence of a byte in a slice.</p>
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<p>This returns the index corresponding to the last occurrence of <code>needle</code> in
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<code>haystack</code>, or <code>None</code> if one is not found.</p>
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<p>While this is operationally the same as something like
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<code>haystack.iter().rposition(|&b| b == needle)</code>, <code>memrchr</code> will use a highly
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optimized routine that can be up to an order of magnitude faster in some
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cases.</p>
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<h1 id="example" class="section-header"><a href="#example">Example</a></h1>
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<p>This shows how to find the last position of a byte in a byte 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">memchr</span>::<span class="ident">memrchr</span>;
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<span class="kw">let</span> <span class="ident">haystack</span> <span class="op">=</span> <span class="string">b"the quick brown fox"</span>;
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">memrchr</span>(<span class="string">b'o'</span>, <span class="ident">haystack</span>), <span class="prelude-val">Some</span>(<span class="number">17</span>));</pre></div>
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