91 lines
7.6 KiB
HTML
91 lines
7.6 KiB
HTML
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<title>std::auto_ptr<T>::auto_ptr</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_memory_auto_ptr_auto_ptr 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::auto_ptr<T>::</span>auto_ptr</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-auto_ptr.html">auto ptr</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span> auto_ptr<span class="br0">(</span> X<span class="sy2">*</span> p <span class="sy1">=</span> <span class="nu0">0</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>(1)</td>
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<td><span class="t-mark">(C++11 中弃用)</span><br />
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<span class="t-mark-rev t-until-cxx17">(C++17 中移除)</span></td>
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<div><span class="mw-geshi cpp source-cpp">auto_ptr<span class="br0">(</span> auto_ptr<span class="sy3">&</span> r <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>(2)</td>
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<td><span class="t-mark">(C++11 中弃用)</span><br />
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<span class="t-mark-rev t-until-cxx17">(C++17 中移除)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> Y <span class="sy1">></span><br />
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auto_ptr<span class="br0">(</span> auto_ptr<span class="sy1"><</span>Y<span class="sy1">></span><span class="sy3">&</span> r <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>(3)</td>
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<td><span class="t-mark">(C++11 中弃用)</span><br />
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<span class="t-mark-rev t-until-cxx17">(C++17 中移除)</span></td>
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<tr class="t-dcl t-until-cxx17">
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<div><span class="mw-geshi cpp source-cpp">auto_ptr<span class="br0">(</span> auto_ptr_ref<span class="sy1"><</span>X<span class="sy1">></span> m <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>(4)</td>
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<td><span class="t-mark">(C++11 中弃用)</span><br />
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<span class="t-mark-rev t-until-cxx17">(C++17 中移除)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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<p>从指代待管理对象的指针构造 <code>auto_ptr</code> 。</p>
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<div class="t-li1"><span class="t-li">1)</span> 以指针 <code>p</code> 构造 <code>auto_ptr</code> 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 以 <code>r</code> 所保有的指针构造 <code>auto_ptr</code> 。调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">r.<span class="me1">release</span><span class="br0">(</span><span class="br0">)</span></span></span> 获取该对象的所有权。</div>
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<div class="t-li1"><span class="t-li">3)</span> 同 (2) 。 <span class="t-c"><span class="mw-geshi cpp source-cpp">Y<span class="sy2">*</span></span></span> 必须可隐式转换为 <span class="t-c"><span class="mw-geshi cpp source-cpp">T<span class="sy2">*</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">4)</span> 以 <code>m</code> 所指代的 <code>auto_ptr</code> 实例中保有的指针构造 <code>auto_ptr</code> 。对 <code>m</code> 所保有的 <code>auto_ptr p</code> 调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">p.<span class="me1">release</span><span class="br0">(</span><span class="br0">)</span></span></span> 以获取该对象的所有权。</div>
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<div class="t-li1"><span class="t-li"></span> <code>auto_ptr_ref</code> 是保有到 <code>auto_ptr</code> 引用的实现定义类型。 <span class="t-lc"><a href="cpp-memory-auto_ptr.html">std::auto_ptr</a></span> <a href="cpp-memory-auto_ptr-operator_auto_ptr.html">可隐式转换成</a>此类型并可从它<a href="cpp-memory-auto_ptr-operator=.html">赋值</a>。允许实现以不同的名称提供该模板，或以其他方式实现等价的功能。</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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<td>p</td>
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<td>-</td>
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<td>指向待管理对象的指针</td>
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</tr>
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<tr class="t-par">
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<td>r</td>
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<td>-</td>
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<td>另一 <code>auto_ptr</code> ，从它传递所有权</td>
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</tr>
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<tr class="t-par">
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<td>m</td>
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<td>-</td>
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<td>保有到 <code>auto_ptr</code> 的引用的实现定义类型对象</td>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p>源自 <code>auto_ptr_ref</code> 的构造函数和复制赋值运算符允许从无名临时量复制构造和赋值 <span class="t-lc"><a href="cpp-memory-auto_ptr.html">std::auto_ptr</a></span> 。因为其复制构造函数与复制赋值运算符以非 const 引用接收参数，它们不能直接绑定右值。然而能执行<a href="cpp-memory-auto_ptr-operator_auto_ptr.html">用户定义转换</a>（释放原 <code>auto_ptr</code> ），之后再调用以值接收 <code>auto_ptr_ref</code> 的构造函数或复制赋值运算符。这是<a href="cpp-utility-move.html">移动语义</a>的早期实现。</p>
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