292 lines
16 KiB
HTML
292 lines
16 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>std::bad_alloc</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_memory_new_bad_alloc 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::</span>bad_alloc</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>‎ | <a href="cpp-memory-new.html">new</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-new.html"><new></a></code></div>
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<td></td>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">class</span> bad_alloc<span class="sy4">;</span></span></div>
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<p><code>std::bad_alloc</code> 是<a href="cpp-memory-new-operator_new.html">分配函数</a>作为异常抛出的对象类型，以报告存储分配失败。</p>
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<div class="t-inheritance-diagram">
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<div class="noresize" style="height: 40px; width: 243px;"><map name="ImageMap_1_1921001904" id="ImageMap_1_1921001904">
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<area href="cpp-error-exception.html" shape="rect" coords="5,4,107,36" alt="cpp/error/exception" /></map><img alt="std-bad alloc-inheritance.svg" src="std-bad_alloc-inheritance.svg" width="243" height="40" usemap="#ImageMap_1_1921001904" /></div>
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<div style="text-align:center;">
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<p><span style="font-size:0.7em; line-height:130%">继承图</span></p>
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</div>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
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<table class="t-dsc-begin">
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><span class="t-lines"><span>(构造函数)</span></span></div>
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</div>
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</td>
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<td>构造新的 <code>bad_alloc</code> 对象<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><span class="t-lines"><span>operator=</span></span></div>
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</div>
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</td>
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<td>替换 <code>bad_alloc</code> 对象<br />
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<span class="t-mark">(公开成员函数)</span></td>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><span class="t-lines"><span>what</span></span></div>
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</td>
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<td>返回解释字符串<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</table>
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<div class="t-member">
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<h2><span class="mw-headline" id="std::bad_alloc::bad_alloc"><span style="font-size:0.7em; line-height:130%">std::bad_alloc::</span>bad_alloc</span></h2>
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<td rowspan="142">(1)</td>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp">bad_alloc<span class="br0">(</span><span class="br0">)</span> <span class="kw1">throw</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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<div><span class="mw-geshi cpp source-cpp">bad_alloc<span class="br0">(</span><span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<tbody></tbody>
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<td rowspan="142">(2)</td>
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<div><span class="mw-geshi cpp source-cpp">bad_alloc<span class="br0">(</span> <span class="kw4">const</span> bad_alloc<span class="sy3">&</span> other <span class="br0">)</span> <span class="kw1">throw</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp">bad_alloc<span class="br0">(</span> <span class="kw4">const</span> bad_alloc<span class="sy3">&</span> other <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<p>构造新的拥有实现定义的空终止字节字符串的 <code>bad_alloc</code> 对象，字符串能通过 <a href="cpp-error-exception-what.html"><tt>what()</tt></a> 访问。</p>
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<div class="t-li1"><span class="t-li">1)</span> 默认构造函数。</div>
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<div class="t-li1"><span class="t-li">2)</span> 复制构造函数。<span class="t-rev-inl t-since-cxx11"><span>若 <code>*this</code> 与 <code>other</code> 均拥有动态类型 <code>std::bad_alloc</code> 则 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-byte-strcmp.html"><span class="kw1145">std::<span class="me2">strcmp</span></span></a><span class="br0">(</span>what<span class="br0">(</span><span class="br0">)</span>, other.<span class="me1">what</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">0</span></span></span> 。</span> <span><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></span></span></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>other</td>
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<td>-</td>
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<td>要复制的另一异常对象</td>
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</tr>
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</table>
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</div>
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<div class="t-member">
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<h2><span class="mw-headline" id="std::bad_alloc::operator.3D"><span style="font-size:0.7em; line-height:130%">std::bad_alloc::</span>operator=</span></h2>
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<div><span class="mw-geshi cpp source-cpp">bad_alloc<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> bad_alloc<span class="sy3">&</span> other <span class="br0">)</span> <span class="kw1">throw</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</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-until-cxx11">(C++11 前)</span></td>
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<tr class="t-dcl t-since-cxx11">
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<div><span class="mw-geshi cpp source-cpp">bad_alloc<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> bad_alloc<span class="sy3">&</span> other <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</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-cxx11">(C++11 起)</span></td>
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<p>以 <code>other</code> 的内容赋值。<span class="t-rev-inl t-since-cxx11"><span>若 <code>*this</code> 与 <code>other</code> 均拥有动态类型 <code>std::bad_alloc</code> 则赋值后 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-byte-strcmp.html"><span class="kw1145">std::<span class="me2">strcmp</span></span></a><span class="br0">(</span>what<span class="br0">(</span><span class="br0">)</span>, other.<span class="me1">what</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">0</span></span></span> 。</span> <span><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></span></span></p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0_2">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>other</td>
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<td>-</td>
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<td>用以赋值的另一异常对象</td>
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</tr>
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</table>
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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><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span></p>
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</div>
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<div class="t-member">
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<h2><span class="mw-headline" id="std::bad_alloc::what"><span style="font-size:0.7em; line-height:130%">std::bad_alloc::</span>what</span></h2>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">virtual</span> <span class="kw4">const</span> <span class="kw4">char</span><span class="sy2">*</span> what<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">throw</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</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-until-cxx11">(C++11 前)</span></td>
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<tr class="t-dcl t-since-cxx11">
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">virtual</span> <span class="kw4">const</span> <span class="kw4">char</span><span class="sy2">*</span> what<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</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-cxx11">(C++11 起)</span></td>
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<tbody>
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<p>返回解释字符串。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0_3">参数</span></h3>
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<p>（无）</p>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC_2">返回值</span></h3>
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<p>指向有解释信息的空终止字符串的指针。该字符串适合转换并显示为 <span class="t-lc"><a href="cpp-string-basic_string.html">std::wstring</a></span> 。保证该指针至少到获得它来源的异常对象被销毁，或在该异常对象上调用非 const 成员函数（例如复制赋值运算符）为止合法。</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>允许但不要求实现覆写 <code>what()</code> 。</p>
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</div>
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<div class="t-inherited">
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<h2><span class="mw-headline" id=".E7.BB.A7.E6.89.BF.E8.87.AA_std::exception">继承自 <a href="cpp-error-exception.html"><span style="font-size:0.7em; line-height:130%">std::</span>exception</a></span></h2>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0_2">成员函数</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 t-dsc-member-nobold-div">
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<div><a href="cpp-error-exception-~exception.html"><span class="t-lines"><span>(析构函数)</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
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</div>
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</td>
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<td>析构该异常对象<br />
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<span class="t-mark">(<code>std::exception</code> 的虚公开成员函数)</span></td>
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</tr>
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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="cpp-error-exception-what.html"><span class="t-lines"><span>what</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
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</div>
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</td>
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<td>返回解释性字符串<br />
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<span class="t-mark">(<code>std::exception</code> 的虚公开成员函数)</span></td>
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</table>
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</div>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <new></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw1">try</span> <span class="br0">{</span>
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<span class="kw1">while</span> <span class="br0">(</span><span class="kw2">true</span><span class="br0">)</span> <span class="br0">{</span>
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new <span class="kw4">int</span><span class="br0">[</span>100000000ul<span class="br0">]</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span> <span class="kw1">catch</span> <span class="br0">(</span><span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">bad_alloc</span><span class="sy3">&</span> e<span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Allocation failed: "</span> <span class="sy1"><<</span> e.<span class="me1">what</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>可能的输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">Allocation failed: std::bad_alloc</pre></div>
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</div>
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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="cpp-memory-new-operator_new.html"><span class="t-lines"><span>operator new</span><span>operator new[]</span></span></a></div>
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</div>
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</td>
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<td>分配函数<br />
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<span class="t-mark">(函数)</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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</html>
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