106 lines
5.0 KiB
HTML
106 lines
5.0 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>ATOMIC_VAR_INIT</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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</head>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_atomic_ATOMIC_VAR_INIT skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading">ATOMIC_VAR_INIT</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-atomic.html">atomic</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dsc-header">
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<td>
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<div>定义于头文件 <code><stdatomic.h></code></div>
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</td>
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<td></td>
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<td></td>
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</tr>
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<tr class="t-dcl t-since-c11">
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<td>
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<div><span class="mw-geshi c source-c"><span class="co2">#define ATOMIC_VAR_INIT(value) /* unspecified */</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-c11">(C11 起)</span><br />
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<span class="t-mark">(C17 中弃用)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<p>展开成能用于初始化类型同 <code>value</code> 的原子对象的表达式。</p>
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<p>拥有自动存储期而不显式初始化的原子对象的初始值不确定。不过，静态和线程局域对象的默认（零）初始化产生合法值。</p>
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<p>初始化原子对象时，任何同时访问，即使通过原子操作，都是数据竞争（若立即将地址以 <span class="t-lc"><a href="c-atomic-memory_order.html">memory_order_relaxed</a></span> 操作传递给另一线程，就可能发生）。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>此宏曾是 C11 原子类型设计早期方案的一部分。在 C11 中不需要，于 C17 中弃用，并计划于 C2x 中移除。</p>
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<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
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<p>下列更改行为的缺陷报告追溯地应用于以前出版的 C 标准。</p>
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<table class="dsctable" style="font-size:0.8em">
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<tr>
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<th>DR</th>
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<th>应用于</th>
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<th>出版时的行为</th>
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<th>正确行为</th>
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</tr>
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<tr>
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<td><a rel="nofollow" class="external text" href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2396.htm#dr_485">DR 485</a></td>
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<td>C11</td>
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<td>规范冗余并与核心语言矛盾</td>
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<td>已更正</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">引用</span></h3>
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<div class="t-ref-std-17">
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<ul>
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<li>C17 标准（ISO/IEC 9899:2018）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.17.2.1 The ATOMIC_VAR_INIT macro (p: 201)</li>
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</ul>
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</dd>
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</dl>
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</div>
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<div class="t-ref-std-11">
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<ul>
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<li>C11 标准（ISO/IEC 9899:2011）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.17.2.1 The ATOMIC_VAR_INIT macro (p: 274)</li>
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</ul>
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</dd>
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</dl>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="c-atomic-ATOMIC_FLAG_INIT.html"><span class="t-lines"><span>ATOMIC_FLAG_INIT</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
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</div>
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</td>
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<td>初始化新的 <span class="t-c"><span class="mw-geshi c source-c"><a href="c-atomic-atomic_flag.html"><span class="kw917">atomic_flag</span></a></span></span><br />
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<span class="t-mark">(宏常量)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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