26 lines
6.2 KiB
HTML
26 lines
6.2 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 `format64` fn in crate `ryu`."><meta name="keywords" content="rust, rustlang, rust-lang, format64"><title>ryu::raw::format64 - 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='../../ryu/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'>ryu</a>::<wbr><a href='index.html'>raw</a></p><script>window.sidebarCurrent = {name: 'format64', 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 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/ryu/pretty/mod.rs.html#55-121' title='goto source code'>[src]</a></span><span class='in-band'>Function <a href='../index.html'>ryu</a>::<wbr><a href='index.html'>raw</a>::<wbr><a class="fn" href=''>format64</a></span></h1><pre class='rust fn'><span class="docblock attributes">#[must_use]
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</span>pub unsafe fn format64(f: f64, result: *mut u8) -> usize</pre><div class='docblock'><p>Print f64 to the given buffer and return number of bytes written.</p>
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<p>At most 24 bytes will be written.</p>
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<h2 id="special-cases" class="section-header"><a href="#special-cases">Special cases</a></h2>
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<p>This function <strong>does not</strong> check for NaN or infinity. If the input
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number is not a finite float, the printed representation will be some
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correctly formatted but unspecified numerical value.</p>
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<p>Please check <a href="https://doc.rust-lang.org/std/primitive.f64.html#method.is_finite"><code>is_finite</code></a> yourself before calling this function, or
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check <a href="https://doc.rust-lang.org/std/primitive.f64.html#method.is_nan"><code>is_nan</code></a> and <a href="https://doc.rust-lang.org/std/primitive.f64.html#method.is_infinite"><code>is_infinite</code></a> and handle those cases yourself.</p>
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<h2 id="safety" class="section-header"><a href="#safety">Safety</a></h2>
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<p>The <code>result</code> pointer argument must point to sufficiently many writable bytes
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to hold Ryū's representation of <code>f</code>.</p>
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<h2 id="example" class="section-header"><a href="#example">Example</a></h2>
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<div class='information'><div class='tooltip edition'>ⓘ<span class='tooltiptext'>This code runs with edition 2018</span></div></div><div class="example-wrap"><pre class="rust rust-example-rendered edition ">
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<span class="kw">use</span> <span class="ident">std</span>::{<span class="ident">mem</span>::<span class="ident">MaybeUninit</span>, <span class="ident">slice</span>, <span class="ident">str</span>};
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<span class="kw">let</span> <span class="ident">f</span> <span class="op">=</span> <span class="number">1.234f64</span>;
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<span class="kw">unsafe</span> {
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<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buffer</span> <span class="op">=</span> [<span class="ident">MaybeUninit</span>::<span class="op"><</span><span class="ident">u8</span><span class="op">></span>::<span class="ident">uninit</span>(); <span class="number">24</span>];
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<span class="kw">let</span> <span class="ident">len</span> <span class="op">=</span> <span class="ident">ryu</span>::<span class="ident">raw</span>::<span class="ident">format64</span>(<span class="ident">f</span>, <span class="ident">buffer</span>.<span class="ident">as_mut_ptr</span>() <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">u8</span>);
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<span class="kw">let</span> <span class="ident">slice</span> <span class="op">=</span> <span class="ident">slice</span>::<span class="ident">from_raw_parts</span>(<span class="ident">buffer</span>.<span class="ident">as_ptr</span>() <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">u8</span>, <span class="ident">len</span>);
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<span class="kw">let</span> <span class="ident">print</span> <span class="op">=</span> <span class="ident">str</span>::<span class="ident">from_utf8_unchecked</span>(<span class="ident">slice</span>);
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">print</span>, <span class="string">"1.234"</span>);
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}</pre></div>
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