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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::array&lt;T,N&gt;::</span>at</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-container.html">container</a>&lrm; | <a href="cpp-container-array.html">array</a></span></div>
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<div><span class="mw-geshi cpp source-cpp">reference at<span class="br0">(</span> size_type pos <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx17">(C++17 &#21069;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> reference at<span class="br0">(</span> size_type pos <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp">const_reference at<span class="br0">(</span> size_type pos <span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx14">(C++14 &#21069;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> const_reference at<span class="br0">(</span> size_type pos <span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx14">(C++14 &#36215;)</span></td>
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<p>&#36820;&#22238;&#20301;&#20110;&#25351;&#23450;&#20301;&#32622; <code>pos</code> &#30340;&#20803;&#32032;&#30340;&#24341;&#29992;&#65292;&#26377;&#36793;&#30028;&#26816;&#26597;&#12290;</p>
<p>&#33509; <code>pos</code> &#19981;&#22312;&#23481;&#22120;&#33539;&#22260;&#20869;&#65292;&#21017;&#25243;&#20986; <span class="t-lc"><a href="cpp-error-out_of_range.html">std::out_of_range</a></span> &#31867;&#22411;&#30340;&#24322;&#24120;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>pos</td>
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<td>&#35201;&#36820;&#22238;&#30340;&#20803;&#32032;&#30340;&#20301;&#32622;</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#21040;&#25152;&#38656;&#20803;&#32032;&#30340;&#24341;&#29992;&#12290;</p>
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">&#24322;&#24120;</span></h3>
<p>&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span><span class="br0">(</span>pos <span class="sy1">&lt;</span> size<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span> &#21017;&#25243;&#20986; <span class="t-lc"><a href="cpp-error-out_of_range.html">std::out_of_range</a></span></p>
<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">&#22797;&#26434;&#24230;</span></h3>
<p>&#24120;&#25968;&#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;array&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-container-array.html"><span class="kw1268">std::<span class="me2">array</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span>,<span class="nu0">6</span><span class="sy1">&gt;</span> data <span class="sy1">=</span> <span class="br0">{</span> <span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">4</span>, <span class="nu0">5</span>, <span class="nu0">5</span>, <span class="nu0">6</span> <span class="br0">}</span><span class="sy4">;</span>
<span class="co1">// Set element 1</span>
data.<span class="me1">at</span><span class="br0">(</span><span class="nu0">1</span><span class="br0">)</span> <span class="sy1">=</span> <span class="nu0">88</span><span class="sy4">;</span>
<span class="co1">// Read element 2</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;Element at index 2 has value &quot;</span> <span class="sy1">&lt;&lt;</span> data.<span class="me1">at</span><span class="br0">(</span><span class="nu0">2</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;data size = &quot;</span> <span class="sy1">&lt;&lt;</span> data.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="kw1">try</span> <span class="br0">{</span>
<span class="co1">// Set element 6</span>
data.<span class="me1">at</span><span class="br0">(</span><span class="nu0">6</span><span class="br0">)</span> <span class="sy1">=</span> <span class="nu0">666</span><span class="sy4">;</span>
<span class="br0">}</span> <span class="kw1">catch</span> <span class="br0">(</span><a href="cpp-error-out_of_range.html"><span class="kw768">std::<span class="me2">out_of_range</span></span></a> <span class="kw4">const</span><span class="sy3">&amp;</span> exc<span class="br0">)</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">&lt;&lt;</span> exc.<span class="me1">what</span><span class="br0">(</span><span class="br0">)</span> <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>
<span class="co1">// Print final values</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;data:&quot;</span><span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> elem <span class="sy4">:</span> data<span class="br0">)</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot; &quot;</span> <span class="sy1">&lt;&lt;</span> elem<span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">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>&#21487;&#33021;&#30340;&#36755;&#20986;&#65306;</p>
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<pre class="de1">Element at index 2 has value 4
data size = 6
array::at: __n (which is 6) &gt;= _Nm (which is 6)
data: 1 88 4 5 5 6</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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<div><a href="cpp-container-array-operator_at.html"><span class="t-lines"><span>operator[]</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>&#35775;&#38382;&#25351;&#23450;&#30340;&#20803;&#32032;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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