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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>generate_n</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-algorithm.html">algorithm</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-algorithm.html">&lt;algorithm&gt;</a></code></div>
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<td rowspan="142">(1)</td>
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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> OutputIt, <span class="kw1">class</span> Size, <span class="kw1">class</span> Generator <span class="sy1">&gt;</span><br />
<span class="kw4">void</span> generate_n<span class="br0">(</span> OutputIt first, Size count, Generator g <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 &#21069;)</span></td>
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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> OutputIt, <span class="kw1">class</span> Size, <span class="kw1">class</span> Generator <span class="sy1">&gt;</span><br />
OutputIt generate_n<span class="br0">(</span> OutputIt first, Size count, Generator g <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
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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> OutputIt, <span class="kw1">class</span> Size, <span class="kw1">class</span> Generator <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> OutputIt generate_n<span class="br0">(</span> OutputIt first, Size count, Generator g <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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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> ExecutionPolicy, <span class="kw1">class</span> ForwardIt , <span class="kw1">class</span> Size, <span class="kw1">class</span> Generator <span class="sy1">&gt;</span><br /></span>
<p>ForwardIt generate_n<span class="br0">(</span> ExecutionPolicy<span class="sy3">&amp;&amp;</span> policy, ForwardIt first,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Size count, Generator g <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<div class="t-li1"><span class="t-li">1)</span> &#33509; <code>count&gt;0</code> &#65292;&#21017;&#36171;&#20540;&#32473;&#23450;&#20989;&#25968;&#23545;&#35937; <code>g</code> &#25152;&#29983;&#25104;&#30340;&#20540;&#32473;&#22987;&#20110; <code>first</code> &#30340;&#33539;&#22260;&#30340;&#39318; <code>count</code> &#20010;&#20803;&#32032;&#12290;&#21542;&#21017;&#19981;&#20570;&#20219;&#20309;&#20107;&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#21516; <span class="t-v">(1)</span> &#65292;&#20294;&#25353;&#29031; <code>policy</code> &#25191;&#34892;&#12290;&#27492;&#37325;&#36733;&#20165;&#33509; <span class="t-rev-inl t-until-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-algorithm-is_execution_policy.html"><span class="kw1564">std::<span class="me2">is_execution_policy_v</span></span></a><span class="sy1">&lt;</span><a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1">&lt;</span>ExecutionPolicy<span class="sy1">&gt;&gt;</span></span></span></span> <span><span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></span></span><span class="t-rev-inl t-since-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-algorithm-is_execution_policy.html"><span class="kw1564">std::<span class="me2">is_execution_policy_v</span></span></a><span class="sy1">&lt;</span>std<span class="sy4">::</span><span class="me2">remove_cvref_t</span><span class="sy1">&lt;</span>ExecutionPolicy<span class="sy1">&gt;&gt;</span></span></span></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></span></span> &#20026; true &#25165;&#21442;&#19982;&#37325;&#36733;&#20915;&#35758;&#12290;</div>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>first</td>
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<td>&#35201;&#29983;&#25104;&#30340;&#20803;&#32032;&#33539;&#22260;&#36215;&#22987;</td>
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<td>count</td>
<td>-</td>
<td>&#35201;&#29983;&#25104;&#30340;&#20803;&#32032;&#25968;</td>
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<td>policy</td>
<td>-</td>
<td>&#25152;&#29992;&#30340;&#25191;&#34892;&#31574;&#30053;&#12290;&#32454;&#33410;&#35265;<a href="cpp-algorithm-execution_policy_tag_t.html">&#25191;&#34892;&#31574;&#30053;</a>&#12290;</td>
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<td>g</td>
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<td>&#23558;&#35201;&#35843;&#29992;&#30340;&#29983;&#25104;&#22120;&#20989;&#25968;&#12290;<br />
<p>&#31614;&#21517;&#24212;&#31561;&#20215;&#20110;&#22914;&#19979;&#65306;</p>
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<div><span class="mw-geshi cpp source-cpp">Ret fun<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>&#31867;&#22411; <span class="t-c"><span class="mw-geshi cpp source-cpp">Ret</span></span> &#24517;&#39035;&#20351;&#24471; <span class="t-c"><span class="mw-geshi cpp source-cpp">OutputIt</span></span> &#31867;&#22411;&#23545;&#35937;&#33021;&#34987;&#35299;&#24341;&#29992;&#24182;&#33021;&#34987;&#36171; <span class="t-c"><span class="mw-geshi cpp source-cpp">Ret</span></span> &#31867;&#22411;&#20540;&#12290; &#8203;</p>
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<td colspan="3">&#31867;&#22411;&#35201;&#27714;</td>
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<td colspan="3">-
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<code>OutputIt</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-OutputIterator.html"><span style="font-style:italic">&#32769;&#24335;&#36755;&#20986;&#36845;&#20195;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LegacyOutputIterator)</span></a> &#30340;&#35201;&#27714;&#12290;</td>
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<td colspan="3">-
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<code>ForwardIt</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-ForwardIterator.html"><span style="font-style:italic">&#32769;&#24335;&#21521;&#21069;&#36845;&#20195;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LegacyForwardIterator)</span></a> &#30340;&#35201;&#27714;&#12290;</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>
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<p>&#65288;&#26080;&#65289;</p>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 &#21069;)</span></td>
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<p>&#33509; <code>count&gt;0</code> &#21017;&#20026;&#26368;&#21518;&#34987;&#36171;&#20540;&#20803;&#32032;&#21518;&#19968;&#20301;&#32622;&#30340;&#36845;&#20195;&#22120;&#12290;&#21542;&#21017;&#20026; <code>first</code> &#12290;</p>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">&#22797;&#26434;&#24230;</span></h3>
<p>&#23545;&#20110; <code>count&gt;0</code> &#65292;&#20934;&#30830; <code>count</code> &#27425;&#35843;&#29992; <code>g()</code> &#21644;&#36171;&#20540;&#12290;</p>
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">&#24322;&#24120;</span></h3>
<p>&#25317;&#26377;&#21517;&#20026; <code>ExecutionPolicy</code> &#30340;&#27169;&#26495;&#24418;&#21442;&#30340;&#37325;&#36733;&#25353;&#19979;&#21015;&#26041;&#24335;&#25253;&#21578;&#38169;&#35823;&#65306;</p>
<ul>
<li>&#33509;&#20316;&#20026;&#31639;&#27861;&#19968;&#37096;&#20998;&#35843;&#29992;&#30340;&#20989;&#25968;&#30340;&#25191;&#34892;&#25243;&#20986;&#24322;&#24120;&#65292;&#19988; <code>ExecutionPolicy</code> &#20026;<a href="cpp-algorithm-execution_policy_tag_t.html">&#26631;&#20934;&#31574;&#30053;</a>&#20043;&#19968;&#65292;&#21017;&#35843;&#29992; <span class="t-lc"><a href="cpp-error-terminate.html">std::terminate</a></span> &#12290;&#23545;&#20110;&#20219;&#20309;&#20854;&#20182; <code>ExecutionPolicy</code> &#65292;&#34892;&#20026;&#26159;&#23454;&#29616;&#23450;&#20041;&#30340;&#12290;</li>
<li>&#33509;&#31639;&#27861;&#26080;&#27861;&#20998;&#37197;&#20869;&#23384;&#65292;&#21017;&#25243;&#20986; <span class="t-lc"><a href="cpp-memory-new-bad_alloc.html">std::bad_alloc</a></span> &#12290;</li>
</ul>
<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">&#21487;&#33021;&#30340;&#23454;&#29616;</span></h3>
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<div class="cpp source-cpp">
<pre class="de1"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> OutputIt, <span class="kw1">class</span> Size, <span class="kw1">class</span> Generator <span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="co1">// C++20 &#36215;</span>
OutputIt <span class="co1">// C++11 &#21069;&#20026; void</span>
Ogenerate_n<span class="br0">(</span> OutputIt first, Size count, Generator g <span class="br0">)</span>
<span class="br0">{</span>
<span class="kw1">for</span><span class="br0">(</span> Size i <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> i <span class="sy1">&lt;</span> count<span class="sy4">;</span> <span class="sy2">++</span>i <span class="br0">)</span> <span class="br0">{</span>
<span class="sy2">*</span>first<span class="sy2">++</span> <span class="sy1">=</span> g<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">return</span> first<span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<div class="t-example-live-link"></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="cpp source-cpp">
<pre class="de1"><span class="co2">#include &lt;random&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;iterator&gt;</span>
<span class="co2">#include &lt;algorithm&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-numeric-random-mersenne_twister_engine.html"><span class="kw1489">std::<span class="me2">mt19937</span></span></a> rng<span class="sy4">;</span> <span class="co1">// &#40664;&#35748;&#26500;&#36896;&#65292;&#20197;&#22266;&#23450;&#30340;&#31181;&#23376;&#25773;&#31181;</span>
std<span class="sy4">::</span><span class="me2">generate_n</span><span class="br0">(</span><a href="cpp-iterator-ostream_iterator.html"><span class="kw670">std::<span class="me2">ostream_iterator</span></span></a><span class="sy1">&lt;</span>std<span class="sy4">::</span><span class="me2">mt19937</span><span class="sy4">::</span><span class="me2">result_type</span><span class="sy1">&gt;</span><span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a>, <span class="st0">&quot; &quot;</span><span class="br0">)</span>,
<span class="nu0">5</span>, <a href="cpp-utility-functional-ref.html"><span class="kw1069">std::<span class="me2">ref</span></span></a><span class="br0">(</span>rng<span class="br0">)</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">&#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>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="text source-text">
<pre class="de1">3499211612 581869302 3890346734 3586334585 545404204</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 class="t-dsc-member-div">
<div><a href="cpp-algorithm-fill_n.html"><span class="t-lines"><span>fill_n</span></span></a></div>
</div>
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<td>&#23558;&#19968;&#20010;&#32473;&#23450;&#20540;&#22797;&#21046;&#36171;&#20540;&#32473;&#19968;&#20010;&#33539;&#22260;&#20869;&#30340; N &#20010;&#20803;&#32032;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-generate.html"><span class="t-lines"><span>generate</span></span></a></div>
</div>
</td>
<td>&#23558;&#30456;&#32487;&#30340;&#20989;&#25968;&#35843;&#29992;&#32467;&#26524;&#36171;&#20540;&#32473;&#19968;&#20010;&#33539;&#22260;&#20013;&#30340;&#27599;&#20010;&#20803;&#32032;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-ranges-generate_n.html"><span class="t-lines"><span>ranges::generate_n</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
</div>
</td>
<td>&#20445;&#23384; N &#27425;&#20989;&#25968;&#24212;&#29992;&#30340;&#32467;&#26524;<br />
<span class="t-mark">(niebloid)</span></td>
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<div class="visualClear"></div>
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