174 lines
10 KiB
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174 lines
10 KiB
HTML
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<title>std::atomic_ref<T>::operator+=,-=,&=,|=,^=</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_atomic_atomic_ref_operator_arith2 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::atomic_ref<T>::</span>operator+=,-=,&=,|=,^=</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-atomic.html">atomic</a>‎ | <a href="cpp-atomic-atomic_ref.html">atomic ref</a></span></div>
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<div>仅为 <code>atomic_ref<<i>Integral</i>></code> 与 <code>atomic_ref<<i>Floating</i>></code> 模板特化的成员</div>
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<div><span class="mw-geshi cpp source-cpp">T operator<span class="sy2">+</span><span class="sy1">=</span><span class="br0">(</span> T arg <span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<div>仅为 <code>atomic_ref<T*></code> 模板特化的成员</div>
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<div><span class="mw-geshi cpp source-cpp">T<span class="sy2">*</span> operator<span class="sy2">+</span><span class="sy1">=</span><span class="br0">(</span> <a href="cpp-types-ptrdiff_t.html"><span class="kw101">std::<span class="me2">ptrdiff_t</span></span></a> arg <span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<div>仅为 <code>atomic_ref<<i>Integral</i>></code> 与 <code>atomic_ref<<i>Floating</i>></code> 模板特化的成员</div>
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<div><span class="mw-geshi cpp source-cpp">T operator<span class="sy2">-</span><span class="sy1">=</span><span class="br0">(</span> T arg <span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<div>仅为 <code>atomic_ref<T*></code> 模板特化的成员</div>
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<div><span class="mw-geshi cpp source-cpp">T<span class="sy2">*</span> operator<span class="sy2">-</span><span class="sy1">=</span><span class="br0">(</span> <a href="cpp-types-ptrdiff_t.html"><span class="kw101">std::<span class="me2">ptrdiff_t</span></span></a> arg <span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<div>仅为 <code>atomic_ref<<i>Integral</i>></code> 模板特化的成员</div>
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<div><span class="mw-geshi cpp source-cpp">T operator<span class="sy3">&</span><span class="sy1">=</span><span class="br0">(</span> T arg <span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<div><span class="mw-geshi cpp source-cpp">T operator<span class="sy3">|</span><span class="sy1">=</span><span class="br0">(</span> T arg <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>(4)</td>
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<div><span class="mw-geshi cpp source-cpp">T operator<span class="sy3">^</span><span class="sy1">=</span><span class="br0">(</span> T arg <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>(5)</td>
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<p>原子地以涉及先前值和 <code>arg</code> 的运算的结果替换被引用对象的当前值。这些操作是读修改写操作。</p>
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<div class="t-li1"><span class="t-li">1)</span> 进行原子加法。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> fetch_add<span class="br0">(</span>arg<span class="br0">)</span> <span class="sy2">+</span> arg<span class="sy4">;</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 进行原子减法。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> fetch_sub<span class="br0">(</span>arg<span class="br0">)</span> <span class="sy2">-</span> arg<span class="sy4">;</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">3)</span> 进行原子逐位与。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> fetch_and<span class="br0">(</span>arg<span class="br0">)</span> <span class="sy3">&</span> arg<span class="sy4">;</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">4)</span> 进行原子逐位或。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> fetch_or<span class="br0">(</span>arg<span class="br0">)</span> <span class="sy3">|</span> arg<span class="sy4">;</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">5)</span> 进行原子逐位异或。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> fetch_xor<span class="br0">(</span>arg<span class="br0">)</span> <span class="sy3">^</span> arg<span class="sy4">;</span></span></span> 。</div>
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<p>对于有符号整数类型,定义算术为使用补码。无未定义结果。</p>
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<p>对于浮点类型,有效的<a href="cpp-numeric-fenv.html">浮点环境</a>可能异于调用方线程的浮点环境。不需要操作服从对应的 <span class="t-lc"><a href="cpp-types-numeric_limits.html">std::numeric_limits</a></span> 特性,但鼓励这么做。若结果不是其类型的可表示值,则结果未指定,但操作不会另有未定义行为。</p>
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<p>对于 <code>T*</code> 类型,结果可以为未定义的地址,但操作不会另有未定义行为。若 <code>T</code> 不是对象类型则程序为谬构。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<td>arg</td>
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<td>-</td>
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<td>算术运算的参数</td>
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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>结果值(即应用对应的二元运算符到立即在对应的成员函数效果之前的值的结果)。</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>不同于大多数复合赋值运算符, <code>atomic_ref</code> 的复合赋值运算符不返回到其左侧参数的引用。它们替而返回存储的值的副本。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div><a href="cpp-atomic-atomic_ref-operator_arith.html"><span class="t-lines"><span>operator++</span><span>operator++<span class="t-dsc-small">(int)</span></span><span>operator--</span><span>operator--<span class="t-dsc-small">(int)</span></span></span></a></div>
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<td>原子地将被引用对象增加或减少一<br />
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<span class="t-mark">(公开成员函数)</span></td>
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