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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="This module provides forward and reverse substring search routines."><title>memchr::memmem - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="memchr" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="../sidebar-items.js"></script><script defer src="../../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc mod"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><rustdoc-topbar><h2><a href="#">Module memmem</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../memchr/index.html">memchr</a><span class="version">2.8.0</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">Module memmem</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#example-iterating-over-substring-matches" title="Example: iterating over substring matches">Example: iterating over substring matches</a></li><li><a href="#example-iterating-over-substring-matches-in-reverse" title="Example: iterating over substring matches in reverse">Example: iterating over substring matches in reverse</a></li><li><a href="#example-repeating-a-search-for-the-same-needle" title="Example: repeating a search for the same needle">Example: repeating a search for the same needle</a></li></ul><h3><a href="#structs">Module Items</a></h3><ul class="block"><li><a href="#structs" title="Structs">Structs</a></li><li><a href="#enums" title="Enums">Enums</a></li><li><a href="#functions" title="Functions">Functions</a></li></ul></section><div id="rustdoc-modnav"><h2 class="in-crate"><a href="../index.html">In crate memchr</a></h2></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="../index.html">memchr</a></div><h1>Module <span>memmem</span> <button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../../src/memchr/memmem/mod.rs.html#1-776">Source</a> </span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>This module provides forward and reverse substring search routines.</p>
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<p>Unlike the standard library’s substring search routines, these work on
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arbitrary bytes. For all non-empty needles, these routines will report exactly
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the same values as the corresponding routines in the standard library. For
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the empty needle, the standard library reports matches only at valid UTF-8
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boundaries, where as these routines will report matches at every position.</p>
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<p>Other than being able to work on arbitrary bytes, the primary reason to prefer
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these routines over the standard library routines is that these will generally
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be faster. In some cases, significantly so.</p>
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<h2 id="example-iterating-over-substring-matches"><a class="doc-anchor" href="#example-iterating-over-substring-matches">§</a>Example: iterating over substring matches</h2>
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<p>This example shows how to use <a href="fn.find_iter.html" title="fn memchr::memmem::find_iter"><code>find_iter</code></a> to find occurrences of a substring
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in a haystack.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>memchr::memmem;
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<span class="kw">let </span>haystack = <span class="string">b"foo bar foo baz foo"</span>;
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<span class="kw">let </span><span class="kw-2">mut </span>it = memmem::find_iter(haystack, <span class="string">"foo"</span>);
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<span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="number">0</span>), it.next());
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<span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="number">8</span>), it.next());
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<span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="number">16</span>), it.next());
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<span class="macro">assert_eq!</span>(<span class="prelude-val">None</span>, it.next());</code></pre></div><h2 id="example-iterating-over-substring-matches-in-reverse"><a class="doc-anchor" href="#example-iterating-over-substring-matches-in-reverse">§</a>Example: iterating over substring matches in reverse</h2>
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<p>This example shows how to use <a href="fn.rfind_iter.html" title="fn memchr::memmem::rfind_iter"><code>rfind_iter</code></a> to find occurrences of a substring
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in a haystack starting from the end of the haystack.</p>
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<p><strong>NOTE:</strong> This module does not implement double ended iterators, so reverse
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searches aren’t done by calling <code>rev</code> on a forward iterator.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>memchr::memmem;
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<span class="kw">let </span>haystack = <span class="string">b"foo bar foo baz foo"</span>;
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<span class="kw">let </span><span class="kw-2">mut </span>it = memmem::rfind_iter(haystack, <span class="string">"foo"</span>);
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<span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="number">16</span>), it.next());
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<span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="number">8</span>), it.next());
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<span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="number">0</span>), it.next());
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<span class="macro">assert_eq!</span>(<span class="prelude-val">None</span>, it.next());</code></pre></div><h2 id="example-repeating-a-search-for-the-same-needle"><a class="doc-anchor" href="#example-repeating-a-search-for-the-same-needle">§</a>Example: repeating a search for the same needle</h2>
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<p>It may be possible for the overhead of constructing a substring searcher to be
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measurable in some workloads. In cases where the same needle is used to search
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many haystacks, it is possible to do construction once and thus to avoid it for
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subsequent searches. This can be done with a <a href="struct.Finder.html" title="struct memchr::memmem::Finder"><code>Finder</code></a> (or a <a href="struct.FinderRev.html" title="struct memchr::memmem::FinderRev"><code>FinderRev</code></a> for
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reverse searches).</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>memchr::memmem;
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<span class="kw">let </span>finder = memmem::Finder::new(<span class="string">"foo"</span>);
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<span class="macro">assert_eq!</span>(<span class="prelude-val">Some</span>(<span class="number">4</span>), finder.find(<span class="string">b"baz foo quux"</span>));
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<span class="macro">assert_eq!</span>(<span class="prelude-val">None</span>, finder.find(<span class="string">b"quux baz bar"</span>));</code></pre></div></div></details><h2 id="structs" class="section-header">Structs<a href="#structs" class="anchor">§</a></h2><dl class="item-table"><dt><a class="struct" href="struct.FindIter.html" title="struct memchr::memmem::FindIter">Find<wbr>Iter</a></dt><dd>An iterator over non-overlapping substring matches.</dd><dt><a class="struct" href="struct.FindRevIter.html" title="struct memchr::memmem::FindRevIter">Find<wbr>RevIter</a></dt><dd>An iterator over non-overlapping substring matches in reverse.</dd><dt><a class="struct" href="struct.Finder.html" title="struct memchr::memmem::Finder">Finder</a></dt><dd>A single substring searcher fixed to a particular needle.</dd><dt><a class="struct" href="struct.FinderBuilder.html" title="struct memchr::memmem::FinderBuilder">Finder<wbr>Builder</a></dt><dd>A builder for constructing non-default forward or reverse memmem finders.</dd><dt><a class="struct" href="struct.FinderRev.html" title="struct memchr::memmem::FinderRev">Finder<wbr>Rev</a></dt><dd>A single substring reverse searcher fixed to a particular needle.</dd></dl><h2 id="enums" class="section-header">Enums<a href="#enums" class="anchor">§</a></h2><dl class="item-table"><dt><a class="enum" href="enum.Prefilter.html" title="enum memchr::memmem::Prefilter">Prefilter</a></dt><dd>Prefilter controls whether heuristics are used to accelerate searching.</dd></dl><h2 id="functions" class="section-header">Functions<a href="#functions" class="anchor">§</a></h2><dl class="item-table"><dt><a class="fn" href="fn.find.html" title="fn memchr::memmem::find">find</a></dt><dd>Returns the index of the first occurrence of the given needle.</dd><dt><a class="fn" href="fn.find_iter.html" title="fn memchr::memmem::find_iter">find_<wbr>iter</a></dt><dd>Returns an iterator over all non-overlapping occurrences of a substring in
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a haystack.</dd><dt><a class="fn" href="fn.rfind.html" title="fn memchr::memmem::rfind">rfind</a></dt><dd>Returns the index of the last occurrence of the given needle.</dd><dt><a class="fn" href="fn.rfind_iter.html" title="fn memchr::memmem::rfind_iter">rfind_<wbr>iter</a></dt><dd>Returns a reverse iterator over all non-overlapping occurrences of a
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substring in a haystack.</dd></dl></section></div></main></body></html> |