74 lines
5.2 KiB
HTML
74 lines
5.2 KiB
HTML
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<title>std::pmr::set_default_resource</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_memory_set_default_resource skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::pmr::</span>set_default_resource</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-memory.html">memory</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-memory_resource.html"><memory_resource></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-memory_resource.html"><span class="kw708">std::<span class="me2">pmr</span><span class="sy4">::</span><span class="me2">memory_resource</span></span></a><span class="sy2">*</span> set_default_resource<span class="br0">(</span><a href="cpp-memory-memory_resource.html"><span class="kw708">std::<span class="me2">pmr</span><span class="sy4">::</span><span class="me2">memory_resource</span></span></a><span class="sy2">*</span> r<span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<p>若 <code>r</code> 非空，则设置默认 memory_resource 指针为 <code>r</code> ；否则，设置默认 memory_resource 指针为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-new_delete_resource.html"><span class="kw713">std::<span class="me2">pmr</span><span class="sy4">::</span><span class="me2">new_delete_resource</span></span></a><span class="br0">(</span><span class="br0">)</span></span></span> 。</p>
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<p><i>默认 memory_resource 指针</i>为某些设施在未显式提供 memory_resource 使所用。初始的默认 memory_resource 指针是 <span class="t-lc"><a href="cpp-memory-new_delete_resource.html">std::pmr::new_delete_resource</a></span> 的返回值。</p>
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<p>此函数是线程安全的。每个对 <span class="t-lc"><strong class="selflink">std::pmr::set_default_resource</strong></span> 的调用<i>同步于</i>（见 <span class="t-lc"><a href="cpp-atomic-memory_order.html">std::memory_order</a></span> ） 后继的 <code>std::pmr::set_default_resource</code> 及 <code>std::pmr::get_default_resource</code> 调用。</p>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>返回先前默认 memory_resource 指针的值。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div><a href="cpp-memory-get_default_resource.html"><span class="t-lines"><span>get_default_resource</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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<td>获取缺省 <span class="t-lc"><a href="cpp-memory-memory_resource.html">std::pmr::memory_resource</a></span><br />
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<span class="t-mark">(函数)</span></td>
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<div><a href="cpp-memory-new_delete_resource.html"><span class="t-lines"><span>new_delete_resource</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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<td>返回一个静态的程序范围 <span class="t-lc"><a href="cpp-memory-memory_resource.html">std::pmr::memory_resource</a></span>，它使用全局 <span class="t-lc"><a href="cpp-memory-new-operator_new.html">operator new</a></span> 与 <span class="t-lc"><a href="cpp-memory-new-operator_delete.html">operator delete</a></span> 分配和解分配内存<br />
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<span class="t-mark">(函数)</span></td>
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