55 lines
3.0 KiB
HTML
55 lines
3.0 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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<title>std::pmr::null_memory_resource</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_memory_null_memory_resource skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::pmr::</span>null_memory_resource</h1>
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<div id="bodyContent">
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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 id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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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> null_memory_resource<span class="br0">(</span><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>返回指向不进行任何分配的 <code>memory_resource</code> 的指针。</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>返回指针 <code>p</code> ，指向导出自 <span class="t-lc"><a href="cpp-memory-memory_resource.html">std::pmr::memory_resource</a></span> 类型的静态存储期对象，它拥有下列属性：</p>
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<ul>
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<li>其 <code>allocate()</code> 函数始终抛出 <span class="t-lc"><a href="cpp-memory-new-bad_alloc.html">std::bad_alloc</a></span> ；</li>
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<li>其 <code>deallocate()</code> 函数无效果；</li>
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<li>对于任何 <code>memory_resource</code> <code>r</code> ， <code>p->is_equal(r)</code> 返回 <code>&r == p</code> 。</li>
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</ul>
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<p>每次调用此函数都返回相同值。</p>
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