269 lines
16 KiB
HTML
269 lines
16 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::bad_weak_ptr</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_bad_weak_ptr 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>bad_weak_ptr</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-memory.html">memory</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-memory.html"><memory></a></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx11">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">class</span> bad_weak_ptr<span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p><code>std::bad_weak_ptr</code> 是 <span class="t-lc"><a href="cpp-memory-shared_ptr.html">std::shared_ptr</a></span> 以 <span class="t-lc"><a href="cpp-memory-weak_ptr.html">std::weak_ptr</a></span> 为参数的构造函数，在 <span class="t-lc"><a href="cpp-memory-weak_ptr.html">std::weak_ptr</a></span> 指代已被删除的对象时，作为异常抛出的对象类型。</p>
|
|
<div class="t-inheritance-diagram">
|
|
<div class="center">
|
|
<div class="noresize" style="height: 40px; width: 243px;"><map name="ImageMap_1_974209156" id="ImageMap_1_974209156">
|
|
<area href="cpp-error-exception.html" shape="rect" coords="5,4,107,36" alt="cpp/error/exception" /></map><img alt="std-bad weak ptr-inheritance.svg" src="std-bad_weak_ptr-inheritance.svg" width="243" height="40" usemap="#ImageMap_1_974209156" /></div>
|
|
</div>
|
|
<div style="text-align:center;">
|
|
<p><span style="font-size:0.7em; line-height:130%">继承图</span></p>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div t-dsc-member-nobold-div">
|
|
<div><span class="t-lines"><span>(构造函数)</span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>构造新的 <code>bad_weak_ptr</code> 对象<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><span class="t-lines"><span>operator=</span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>替换 <code>bad_weak_ptr</code> 对象<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><span class="t-lines"><span>what</span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>返回解释字符串<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::bad_weak_ptr::bad_weak_ptr"><span style="font-size:0.7em; line-height:130%">std::bad_weak_ptr::</span>bad_weak_ptr</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx11">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp">bad_weak_ptr<span class="br0">(</span><span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(1)</td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx11">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp">bad_weak_ptr<span class="br0">(</span> <span class="kw4">const</span> bad_weak_ptr<span class="sy3">&</span> other <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>构造新的拥有实现定义的空终止字节字符串的 <code>bad_weak_ptr</code> 对象，字符串能通过 <a href="cpp-error-exception-what.html"><tt>what()</tt></a> 访问。</p>
|
|
<div class="t-li1"><span class="t-li">1)</span> 默认构造函数。</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 复制构造函数。若 <code>*this</code> 与 <code>other</code> 均拥有动态类型 <code>std::bad_weak_ptr</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> 。</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td>other</td>
|
|
<td>-</td>
|
|
<td>要复制的另一异常对象</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::bad_weak_ptr::operator.3D"><span style="font-size:0.7em; line-height:130%">std::bad_weak_ptr::</span>operator=</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx11">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp">bad_weak_ptr<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> bad_weak_ptr<span class="sy3">&</span> other <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>以 <code>other</code> 的内容赋值。若 <code>*this</code> 与 <code>other</code> 均拥有动态类型 <code>std::bad_weak_ptr</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> 。</p>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0_2">参数</span></h3>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td>other</td>
|
|
<td>-</td>
|
|
<td>用以赋值的另一异常对象</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span></p>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::bad_weak_ptr::what"><span style="font-size:0.7em; line-height:130%">std::bad_weak_ptr::</span>what</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx11">
|
|
<td>
|
|
<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>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>返回解释字符串。</p>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0_3">参数</span></h3>
|
|
<p>（无）</p>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC_2">返回值</span></h3>
|
|
<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>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<p>允许但不要求实现覆写 <code>what()</code> 。</p>
|
|
</div>
|
|
<div class="t-inherited">
|
|
<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>
|
|
<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>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div t-dsc-member-nobold-div">
|
|
<div><a href="cpp-error-exception-~exception.html"><span class="t-lines"><span>(析构函数)</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>析构该异常对象<br />
|
|
<span class="t-mark">(<code>std::exception</code> 的虚公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-error-exception-what.html"><span class="t-lines"><span>what</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>返回解释性字符串<br />
|
|
<span class="t-mark">(<code>std::exception</code> 的虚公开成员函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<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 <memory></span>
|
|
<span class="co2">#include <iostream></span>
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> p1<span class="br0">(</span>new <span class="kw4">int</span><span class="br0">(</span><span class="nu0">42</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="cpp-memory-weak_ptr.html"><span class="kw741">std::<span class="me2">weak_ptr</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> wp<span class="br0">(</span>p1<span class="br0">)</span><span class="sy4">;</span>
|
|
p1.<span class="me1">reset</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="kw1">try</span> <span class="br0">{</span>
|
|
<a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> p2<span class="br0">(</span>wp<span class="br0">)</span><span class="sy4">;</span>
|
|
<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_weak_ptr</span><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="br0">}</span></pre></div>
|
|
</div>
|
|
<p>可能的输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">std::bad_weak_ptr</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
|
|
<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>
|
|
<table class="dsctable" style="font-size:0.8em">
|
|
<tr>
|
|
<th>DR</th>
|
|
<th>应用于</th>
|
|
<th>出版时的行为</th>
|
|
<th>正确行为</th>
|
|
</tr>
|
|
<tr>
|
|
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2376">LWG 2376</a></td>
|
|
<td>C++11</td>
|
|
<td>要求在默认构造的 <code>bad_weak_ptr</code> 上调用 <code>what</code> 返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">"bad_weak_ptr"</span></span></span></td>
|
|
<td>返回值为实现定义</td>
|
|
</tr>
|
|
</table>
|
|
<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-shared_ptr.html"><span class="t-lines"><span>shared_ptr</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>拥有共享对象所有权语义的智能指针<br />
|
|
<span class="t-mark">(类模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-memory-weak_ptr.html"><span class="t-lines"><span>weak_ptr</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>到 <span class="t-lc"><a href="cpp-memory-shared_ptr.html">std::shared_ptr</a></span> 所管理对象的弱引用<br />
|
|
<span class="t-mark">(类模板)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|