102 lines
5.7 KiB
HTML
102 lines
5.7 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>std::nothrow</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_memory_new_nothrow skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>nothrow</h1>
|
|
<div id="bodyContent">
|
|
<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>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dsc-header">
|
|
<td>
|
|
<div>定义于头文件 <code><a href="cpp-header-new.html"><new></a></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl">
|
|
<td class="t-dcl-nopad">
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">extern</span> <span class="kw4">const</span> <a href="cpp-memory-new-nothrow_t.html"><span class="kw696">std::<span class="me2">nothrow_t</span></span></a> nothrow<span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td class="t-dcl-nopad"></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p><code>std::nothrow</code> 是 <span class="t-lc"><a href="cpp-memory-new-nothrow_t.html">std::nothrow_t</a></span> 类型的常量，用于区分抛出与不抛出<a href="cpp-memory-new-operator_new.html">分配函数</a>的重载。</p>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="co2">#include <iostream></span>
|
|
<span class="co2">#include <new></span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw1">try</span> <span class="br0">{</span>
|
|
<span class="kw1">while</span> <span class="br0">(</span><span class="kw2">true</span><span class="br0">)</span> <span class="br0">{</span>
|
|
new <span class="kw4">int</span><span class="br0">[</span>100000000ul<span class="br0">]</span><span class="sy4">;</span> <span class="co1">// 抛出重载</span>
|
|
<span class="br0">}</span>
|
|
<span class="br0">}</span> <span class="kw1">catch</span> <span class="br0">(</span><span class="kw4">const</span> <a href="cpp-memory-new-bad_alloc.html"><span class="kw693">std::<span class="me2">bad_alloc</span></span></a><span class="sy3">&</span> e<span class="br0">)</span> <span class="br0">{</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <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>
|
|
<span class="br0">}</span>
|
|
|
|
<span class="kw1">while</span> <span class="br0">(</span><span class="kw2">true</span><span class="br0">)</span> <span class="br0">{</span>
|
|
<span class="kw4">int</span><span class="sy2">*</span> p <span class="sy1">=</span> new<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">nothrow</span><span class="br0">)</span> <span class="kw4">int</span><span class="br0">[</span>100000000ul<span class="br0">]</span><span class="sy4">;</span> <span class="co1">// 不抛出重载</span>
|
|
<span class="kw1">if</span> <span class="br0">(</span>p <span class="sy1">==</span> nullptr<span class="br0">)</span> <span class="br0">{</span>
|
|
<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 returned nullptr<span class="es1">\n</span>"</span><span class="sy4">;</span>
|
|
<span class="kw1">break</span><span class="sy4">;</span>
|
|
<span class="br0">}</span>
|
|
<span class="br0">}</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">std::bad_alloc
|
|
Allocation returned nullptr</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-memory-new-nothrow_t.html"><span class="t-lines"><span>nothrow_t</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>用于选择不抛出<i>分配函数</i>的标签类型<br />
|
|
<span class="t-mark">(类)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-memory-new-operator_new.html"><span class="t-lines"><span>operator new</span><span>operator new[]</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>分配函数<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|