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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="A short-hand constructor for building a `&[u8]`."><title>B in bstr - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../static.files/rustdoc-ac92e1bbe349e143.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="bstr" data-themes="" data-resource-suffix="" data-rustdoc-version="1.76.0 (07dca489a 2024-02-04)" data-channel="1.76.0" data-search-js="search-2b6ce74ff89ae146.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../static.files/storage-f2adc0d6ca4d09fb.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-305769736d49e732.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-feafe1bb7466e4bd.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc fn"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../bstr/index.html">bstr</a><span class="version">1.9.1</span></h2></div><div class="sidebar-elems"></div></nav><div class="sidebar-resizer"></div>
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<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../bstr/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Function <a href="index.html">bstr</a>::<wbr><a class="fn" href="#">B</a><button id="copy-path" title="Copy item path to clipboard"><img src="../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../src/bstr/ext_slice.rs.html#75-77">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>−</span>]</button></span></div><pre class="rust item-decl"><code>pub fn B<'a, B: ?<a class="trait" href="https://doc.rust-lang.org/1.76.0/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="https://doc.rust-lang.org/1.76.0/core/convert/trait.AsRef.html" title="trait core::convert::AsRef">AsRef</a><[<a class="primitive" href="https://doc.rust-lang.org/1.76.0/std/primitive.u8.html">u8</a>]>>(bytes: <a class="primitive" href="https://doc.rust-lang.org/1.76.0/std/primitive.reference.html">&'a B</a>) -> &'a [<a class="primitive" href="https://doc.rust-lang.org/1.76.0/std/primitive.u8.html">u8</a>] <a href="#" class="tooltip" data-notable-ty="&'a [u8]">ⓘ</a></code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>A short-hand constructor for building a <code>&[u8]</code>.</p>
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<p>This idiosyncratic constructor is useful for concisely building byte string
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slices. Its primary utility is in conveniently writing byte string literals
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in a uniform way. For example, consider this code that does not compile:</p>
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<div class="example-wrap ignore"><a href="#" class="tooltip" title="This example is not tested">ⓘ</a><pre class="rust rust-example-rendered"><code><span class="kw">let </span>strs = <span class="macro">vec!</span>[<span class="string">b"a"</span>, <span class="string">b"xy"</span>];</code></pre></div>
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<p>The above code doesn’t compile because the type of the byte string literal
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<code>b"a"</code> is <code>&'static [u8; 1]</code>, and the type of <code>b"xy"</code> is
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<code>&'static [u8; 2]</code>. Since their types aren’t the same, they can’t be stored
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in the same <code>Vec</code>. (This is dissimilar from normal Unicode string slices,
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where both <code>"a"</code> and <code>"xy"</code> have the same type of <code>&'static str</code>.)</p>
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<p>One way of getting the above code to compile is to convert byte strings to
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slices. You might try this:</p>
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<div class="example-wrap ignore"><a href="#" class="tooltip" title="This example is not tested">ⓘ</a><pre class="rust rust-example-rendered"><code><span class="kw">let </span>strs = <span class="macro">vec!</span>[<span class="kw-2">&</span><span class="string">b"a"</span>, <span class="kw-2">&</span><span class="string">b"xy"</span>];</code></pre></div>
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<p>But this just creates values with type <code>& &'static [u8; 1]</code> and
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<code>& &'static [u8; 2]</code>. Instead, you need to force the issue like so:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">let </span>strs = <span class="macro">vec!</span>[<span class="kw-2">&</span><span class="string">b"a"</span>[..], <span class="kw-2">&</span><span class="string">b"xy"</span>[..]];
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<span class="comment">// or
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</span><span class="kw">let </span>strs = <span class="macro">vec!</span>[<span class="string">b"a"</span>.as_ref(), <span class="string">b"xy"</span>.as_ref()];</code></pre></div>
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<p>But neither of these are particularly convenient to type, especially when
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it’s something as common as a string literal. Thus, this constructor
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permits writing the following instead:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>bstr::B;
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<span class="kw">let </span>strs = <span class="macro">vec!</span>[B(<span class="string">"a"</span>), B(<span class="string">b"xy"</span>)];</code></pre></div>
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<p>Notice that this also lets you mix and match both string literals and byte
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string literals. This can be quite convenient!</p>
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</div></details><script type="text/json" id="notable-traits-data">{"&'a [u8]":"<h3>Notable traits for <code>&[<a class=\"primitive\" href=\"https://doc.rust-lang.org/1.76.0/std/primitive.u8.html\">u8</a>]</code></h3><pre><code><div class=\"where\">impl <a class=\"trait\" href=\"https://doc.rust-lang.org/1.76.0/std/io/trait.Read.html\" title=\"trait std::io::Read\">Read</a> for &[<a class=\"primitive\" href=\"https://doc.rust-lang.org/1.76.0/std/primitive.u8.html\">u8</a>]</div>"}</script></section></div></main></body></html> |