<!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 `write` fn in crate `core`.">
<meta name="keywords" content="rust, rustlang, rust-lang, write">
<title>core::ptr::write - Rust</title>
<link rel="stylesheet" type="text/css" href="../../normalize.css">
<link rel="stylesheet" type="text/css" href="../../rustdoc.css">
<link rel="stylesheet" type="text/css" href="../../main.css">
<link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico">
</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">
<a href='../../core/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a>
<p class='location'><a href='../index.html'>core</a>::<wbr><a href='index.html'>ptr</a></p><script>window.sidebarCurrent = {name: 'write', ty: 'fn', relpath: ''};</script><script defer src="sidebar-items.js"></script>
</nav>
<nav class="sub">
<form class="search-form js-only">
<div class="search-container">
<input class="search-input" name="search"
autocomplete="off"
placeholder="Click or press ‘S’ to search, ‘?’ for more options…"
type="search">
</div>
</form>
</nav>
<section id='main' class="content">
<h1 class='fqn'><span class='in-band'>Function <a href='../index.html'>core</a>::<wbr><a href='index.html'>ptr</a>::<wbr><a class="fn" href=''>write</a></span><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='../../src/core/ptr.rs.html#239-241' title='goto source code'>[src]</a></span></h1>
<pre class='rust fn'>pub unsafe fn write<T>(dst: *mut T, src: T)</pre><div class='docblock'><p>Overwrites a memory location with the given value without reading or
dropping the old value.</p>
<h1 id='safety' class='section-header'><a href='#safety'>Safety</a></h1>
<p>This operation is marked unsafe because it accepts a raw pointer.</p>
<p>It does not drop the contents of <code>dst</code>. This is safe, but it could leak
allocations or resources, so care must be taken not to overwrite an object
that should be dropped.</p>
<p>Additionally, it does not drop <code>src</code>. Semantically, <code>src</code> is moved into the
location pointed to by <code>dst</code>.</p>
<p>This is appropriate for initializing uninitialized memory, or overwriting
memory that has previously been <code>read</code> from.</p>
<p>The pointer must be aligned; use <code>write_unaligned</code> if that is not the case.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p>Basic usage:</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">x</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">x</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">i32</span>;
<span class="kw">let</span> <span class="ident">z</span> <span class="op">=</span> <span class="number">12</span>;
<span class="kw">unsafe</span> {
<span class="ident">std</span>::<span class="ident">ptr</span>::<span class="ident">write</span>(<span class="ident">y</span>, <span class="ident">z</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">std</span>::<span class="ident">ptr</span>::<span class="ident">read</span>(<span class="ident">y</span>), <span class="number">12</span>);
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Alet%20mut%20x%20%3D%200%3B%0Alet%20y%20%3D%20%26mut%20x%20as%20*mut%20i32%3B%0Alet%20z%20%3D%2012%3B%0A%0Aunsafe%20%7B%0A%20%20%20%20std%3A%3Aptr%3A%3Awrite(y%2C%20z)%3B%0A%20%20%20%20assert_eq!(std%3A%3Aptr%3A%3Aread(y)%2C%2012)%3B%0A%7D%0A%7D">Run</a></pre>
</div></section>
<section id='search' class="content hidden"></section>
<section class="footer"></section>
<aside id="help" class="hidden">
<div>
<h1 class="hidden">Help</h1>
<div class="shortcuts">
<h2>Keyboard Shortcuts</h2>
<dl>
<dt>?</dt>
<dd>Show this help dialog</dd>
<dt>S</dt>
<dd>Focus the search field</dd>
<dt>⇤</dt>
<dd>Move up in search results</dd>
<dt>⇥</dt>
<dd>Move down in search results</dd>
<dt>⏎</dt>
<dd>Go to active search result</dd>
<dt>+</dt>
<dd>Collapse/expand all sections</dd>
</dl>
</div>
<div class="infos">
<h2>Search Tricks</h2>
<p>
Prefix searches with a type followed by a colon (e.g.
<code>fn:</code>) to restrict the search to a given type.
</p>
<p>
Accepted types are: <code>fn</code>, <code>mod</code>,
<code>struct</code>, <code>enum</code>,
<code>trait</code>, <code>type</code>, <code>macro</code>,
and <code>const</code>.
</p>
<p>
Search functions by type signature (e.g.
<code>vec -> usize</code> or <code>* -> vec</code>)
</p>
</div>
</div>
</aside>
<script>
window.rootPath = "../../";
window.currentCrate = "core";
</script>
<script src="../../main.js"></script>
<script defer src="../../search-index.js"></script>
</body>
</html>
distrib
>
Mageia
>
6
>
armv7hl
>
media
>
core-updates
>
by-pkgid
>
564935689ab5527f955e5449ded02799
>
files
>
1834
