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<title>std::valarray<T>::operator+=,-=,*=,/=,%=,&=,|=,<<=,>>=</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::valarray<T>::</span>operator+=,-=,*=,/=,%=,&=,|=,<<=,>>=</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-numeric.html">numeric</a>‎ | <a href="cpp-numeric-valarray.html">valarray</a></span></div>
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<div><span class="mw-geshi cpp source-cpp">valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">+</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br /></span>
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<p>valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">-</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">*</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">/</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">%</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy3">&</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy3">|</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy3">^</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy1"><<=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span><br /></p>
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy1">>>=</span><span class="br0">(</span> <span class="kw4">const</span> valarray<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> v <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(1)</td>
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<td class="t-dcl-nopad"></td>
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<div><span class="mw-geshi cpp source-cpp">valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">+</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br /></span>
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<p>valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">-</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">*</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">/</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy2">%</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy3">&</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy3">|</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy3">^</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br />
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy1"><<=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span><br /></p>
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valarray<span class="sy1"><</span>T<span class="sy1">></span> operator<span class="sy1">>>=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> val <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(2)</td>
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<td class="t-dcl-nopad"></td>
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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>应用复合赋值运算符到数值数组中的每个元素。</p>
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<div class="t-li1"><span class="t-li">1)</span> 将以应用对应运算符到每个元素先前值和来自 <code>v</code> 的对应元素所获得的值，赋值给每个元素。</div>
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<div class="t-li1"><span class="t-li"></span> 若 <span class="t-c"><span class="mw-geshi cpp source-cpp">size<span class="br0">(</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> v.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span></span></span> 则行为未定义。</div>
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<div class="t-li1"><span class="t-li"></span> 若任何 <code>v</code> 中的值在赋值过程中计算并依赖任何 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 中的值，即赋值右侧的表达式引用到赋值左侧的变量，则行为未定义。</div>
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<div class="t-li1"><span class="t-li">2)</span> 将以应用对应运算符到每个元素先前值和 <code>val</code> 的值所获得的值，赋值给每个元素。</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>v</td>
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<td>-</td>
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<td>另一个数值数组</td>
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</tr>
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<tr class="t-par">
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<td>val</td>
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<td>-</td>
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<td>一个值</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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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<p>可能抛出实现定义的异常。</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>仅若满足下列条件，才能实例化各个运算符：</p>
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<ul>
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<li>所指示的运算符可应用于类型 <code>T</code></li>
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<li>返回值可以无歧义地转换为 <code>T</code> 。</li>
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</ul>
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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 <string_view></span>
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<span class="co2">#include <type_traits></span>
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<span class="co2">#include <valarray></span>
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<span class="kw4">void</span> o<span class="br0">(</span><a href="cpp-string-basic_string_view.html"><span class="kw1248">std::<span class="me2">string_view</span></span></a> rem, <span class="kw4">auto</span> <span class="kw4">const</span><span class="sy3">&</span> v, <span class="kw4">bool</span> nl <span class="sy1">=</span> <span class="kw2">false</span><span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">if</span> <span class="kw4">constexpr</span> <span class="br0">(</span><a href="cpp-types-is_scalar.html"><span class="kw489">std::<span class="me2">is_scalar_v</span></span></a><span class="sy1"><</span><a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>decltype<span class="br0">(</span>v<span class="br0">)</span><span class="sy1">>></span><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> rem <span class="sy1"><<</span> <span class="st0">" : "</span> <span class="sy1"><<</span> v<span class="sy4">;</span>
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<span class="br0">}</span> <span class="kw1">else</span> <span class="br0">{</span>
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<span class="kw1">for</span> <span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> rem <span class="sy1"><<</span> <span class="st0">" : { "</span><span class="sy4">;</span> <span class="kw4">auto</span> <span class="kw4">const</span> e <span class="sy4">:</span> v<span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> e <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"}"</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="br0">(</span>nl <span class="sy4">?</span> <span class="st0">"<span class="es1">\n</span>"</span> <span class="sy4">:</span> <span class="st0">"; "</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</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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<a href="cpp-numeric-valarray.html"><span class="kw1473">std::<span class="me2">valarray</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> x, y<span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"y"</span>, y <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">4</span>, <span class="nu0">3</span>, <span class="nu0">2</span>, <span class="nu0">1</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x += y"</span>, x <span class="sy2">+</span><span class="sy1">=</span> y, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">4</span>, <span class="nu0">3</span>, <span class="nu0">2</span>, <span class="nu0">1</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"y"</span>, y <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">3</span>, <span class="nu0">2</span>, <span class="nu0">1</span>, <span class="nu0">0</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x -= y"</span>, x <span class="sy2">-</span><span class="sy1">=</span> y, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"y"</span>, y <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">5</span>, <span class="nu0">4</span>, <span class="nu0">3</span>, <span class="nu0">2</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x *= y"</span>, x <span class="sy2">*</span><span class="sy1">=</span> y, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">3</span>, <span class="nu0">4</span>, <span class="nu0">7</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"y"</span>, y <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">1</span>, <span class="nu0">3</span>, <span class="nu0">5</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x &= y"</span>, x <span class="sy3">&</span><span class="sy1">=</span> y, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">0</span>, <span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">4</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"y"</span>, y <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">4</span>, <span class="nu0">3</span>, <span class="nu0">2</span>, <span class="nu0">1</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x <<=y"</span>, x <span class="sy1"><<=</span>y, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x += 5"</span>, x <span class="sy2">+</span><span class="sy1">=</span> <span class="nu0">5</span>, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x *= 2"</span>, x <span class="sy2">*</span><span class="sy1">=</span> <span class="nu0">2</span>, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">8</span>, <span class="nu0">6</span>, <span class="nu0">4</span>, <span class="nu0">2</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x /= 2"</span>, x <span class="sy2">/</span><span class="sy1">=</span> <span class="nu0">2</span>, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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o<span class="br0">(</span><span class="st0">"x"</span>, x <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">8</span>, <span class="nu0">4</span>, <span class="nu0">2</span>, <span class="nu0">1</span><span class="br0">}</span><span class="br0">)</span>, o<span class="br0">(</span><span class="st0">"x >>=1"</span>, x <span class="sy1">>>=</span><span class="nu0">1</span>, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>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">x : { 1 2 3 4 }; y : { 4 3 2 1 }; x += y : { 5 5 5 5 }
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x : { 4 3 2 1 }; y : { 3 2 1 0 }; x -= y : { 1 1 1 1 }
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x : { 1 2 3 4 }; y : { 5 4 3 2 }; x *= y : { 5 8 9 8 }
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x : { 1 3 4 7 }; y : { 1 1 3 5 }; x &= y : { 1 1 0 5 }
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x : { 0 1 2 4 }; y : { 4 3 2 1 }; x <<=y : { 0 8 8 8 }
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x : { 1 2 3 4 }; x += 5 : { 6 7 8 9 }
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x : { 1 2 3 4 }; x *= 2 : { 2 4 6 8 }
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x : { 8 6 4 2 }; x /= 2 : { 4 3 2 1 }
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x : { 8 4 2 1 }; x >>=1 : { 4 2 1 0 }</pre></div>
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