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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>mask_array</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-numeric.html">numeric</a>&lrm; | <a href="cpp-numeric-valarray.html">valarray</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-valarray.html">&lt;valarray&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> T <span class="sy1">&gt;</span> <span class="kw1">class</span> mask_array<span class="sy4">;</span></span></div>
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<p><code>std::mask_array</code> &#26159;&#20197;<span class="t-lc">std::valarray&lt;bool&gt;</span> &#20026;&#21442;&#25968;&#30340; <a href="cpp-numeric-valarray-operator_at.html">valarray &#19979;&#26631;&#36816;&#31639;&#31526;</a>&#25152;&#29992;&#30340;&#24110;&#21161;&#27169;&#26495;&#12290;&#23427;&#25317;&#26377;&#24341;&#29992;&#35821;&#20041;&#65292;&#24182;&#25552;&#20379;&#21040;&#30001;&#19979;&#26631;&#23545;&#24212; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-numeric-valarray.html"><span class="kw1473">std::<span class="me2">valarray</span></span></a><span class="sy1">&lt;</span><span class="kw4">bool</span><span class="sy1">&gt;</span></span></span> &#25513;&#30721;&#30340; <code>true</code> &#20540;&#30340;&#20803;&#32032;&#25152;&#32452;&#25104;&#30340; valarray &#23376;&#38598;&#30340;&#35775;&#38382;&#12290;</p>
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">&#25104;&#21592;&#31867;&#22411;</span></h3>
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<td>&#31867;&#22411;</td>
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<td><code>value_type</code></td>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">&#25104;&#21592;&#20989;&#25968;</span></h3>
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<div><a href="cpp-numeric-valarray-mask_array-mask_array.html"><span class="t-lines"><span>(&#26500;&#36896;&#20989;&#25968;)</span></span></a></div>
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<td>&#26500;&#36896;&#19968;&#20010; <code>mask_array</code><br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-numeric-valarray-mask_array-~mask_array.html"><span class="t-lines"><span>(&#26512;&#26500;&#20989;&#25968;)</span></span></a></div>
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<td>&#38144;&#27585;&#19968;&#20010; <code>mask_array</code><br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-numeric-valarray-mask_array-operator=.html"><span class="t-lines"><span>operator=</span></span></a></div>
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<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><a href="cpp-numeric-valarray-mask_array-operator_arith.html"><span class="t-lines"><span>operator+=</span><span>operator-=</span><span>operator*=</span><span>operator/=</span><span>operator%=</span><span>operator&amp;=</span><span>operator|=</span><span>operator^=</span><span>operator&lt;&lt;=</span><span>operator&gt;&gt;=</span></span></a></div>
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<td>&#22312;&#25513;&#30721;&#25152;&#25351;&#20195;&#30340;&#25968;&#32452;&#19978;&#36827;&#34892;&#31639;&#26415;&#36816;&#31639;&#12290;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;valarray&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-numeric-valarray.html"><span class="kw1473">std::<span class="me2">valarray</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> data <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">3</span>,<span class="nu0">4</span>,<span class="nu0">5</span>,<span class="nu0">6</span>,<span class="nu0">7</span>,<span class="nu0">8</span>,<span class="nu0">9</span><span class="br0">}</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;Initial valarray: &quot;</span><span class="sy4">;</span>
<span class="kw1">for</span><span class="br0">(</span><span class="kw4">int</span> n<span class="sy4">:</span> data<span class="br0">)</span> <a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> n <span class="sy1">&lt;&lt;</span> <span class="st0">&#39; &#39;</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
data<span class="br0">[</span>data <span class="sy1">&gt;</span> <span class="nu0">5</span><span class="br0">]</span> <span class="sy1">=</span> <span class="sy2">-</span><span class="nu0">1</span><span class="sy4">;</span>
<span class="co1">// data&gt;5 &#30340;&#31867;&#22411;&#26159; std::valarray&lt;bool&gt;</span>
<span class="co1">// data[data&gt;5] &#30340;&#31867;&#22411;&#26159; std::mask_array&lt;int&gt;</span>
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;After v[v&gt;5]=-1: &quot;</span><span class="sy4">;</span>
<span class="kw1">for</span><span class="br0">(</span><span class="kw4">int</span> n<span class="sy4">:</span> data<span class="br0">)</span> <a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> n <span class="sy1">&lt;&lt;</span> <span class="st0">&#39; &#39;</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
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<pre class="de1">Initial valarray: 0 1 2 3 4 5 6 7 8 9
After v[v&gt;5]=-1: 0 1 2 3 4 5 -1 -1 -1 -1</pre></div>
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