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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>inner_product</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-numeric.html">&lt;numeric&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> InputIt1, <span class="kw1">class</span> InputIt2, <span class="kw1">class</span> T <span class="sy1">&gt;</span><br /></span>
<p>T inner_product<span class="br0">(</span> InputIt1 first1, InputIt1 last1,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;InputIt2 first2, T init <span class="br0">)</span><span class="sy4">;</span></div>
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<td><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> InputIt1, <span class="kw1">class</span> InputIt2, <span class="kw1">class</span> T <span class="sy1">&gt;</span><br /></span>
<p><span class="kw4">constexpr</span> T inner_product<span class="br0">(</span> InputIt1 first1, InputIt1 last1,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;InputIt2 first2, T init <span class="br0">)</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<td rowspan="142">(2)</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> InputIt1, <span class="kw1">class</span> InputIt2, <span class="kw1">class</span> T,<br /></span>
<p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">class</span> BinaryOperation1, <span class="kw1">class</span> BinaryOperation2<span class="sy1">&gt;</span><br />
T inner_product<span class="br0">(</span> InputIt1 first1, InputIt1 last1,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;InputIt2 first2, T init,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;BinaryOperation1 op1,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;BinaryOperation2 op2 <span class="br0">)</span><span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></td>
<td><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> InputIt1, <span class="kw1">class</span> InputIt2, <span class="kw1">class</span> T,<br /></span>
<p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw1">class</span> BinaryOperation1, <span class="kw1">class</span> BinaryOperation2<span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> T inner_product<span class="br0">(</span> InputIt1 first1, InputIt1 last1,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;InputIt2 first2, T init,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;BinaryOperation1 op1,<br /></p>
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;BinaryOperation2 op2 <span class="br0">)</span><span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<p>&#35745;&#31639;&#20869;&#31215;&#65288;&#21363;&#31215;&#20043;&#21644;&#65289;&#25110;&#22312;&#33539;&#22260; <code>[first1, last1)</code> &#21644;&#22987;&#20110; <code>first2</code> &#30340;&#33539;&#22260;&#19978;&#36827;&#34892;&#26377;&#24207;&#26144;&#23556;/&#35268;&#32422;&#25805;&#20316;&#12290;</p>
<div class="t-li1"><span class="t-li">1)</span> &#20197;&#21021;&#20540; <code>init</code> &#21021;&#22987;&#21270;&#31215;&#32047;&#22120; <code>acc</code> &#65292;&#28982;&#21518;
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<p>&#20197;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp">acc <span class="sy1">=</span> acc <span class="sy2">+</span> <span class="sy2">*</span>first1 <span class="sy2">*</span> <span class="sy2">*</span>first2</span></span> &#20462;&#25913;&#23427;&#65292;&#20877;&#20197;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp">acc <span class="sy1">=</span> acc <span class="sy2">+</span> <span class="sy2">*</span><span class="br0">(</span>first1<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span> <span class="sy2">*</span> <span class="sy2">*</span><span class="br0">(</span>first2<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span></span></span> &#20462;&#25913;&#23427;&#65292;&#20197;&#27492;&#31867;&#25512;</p>
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<td><span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
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<p>&#20197;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp">acc <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span> <span class="sy2">+</span> <span class="sy2">*</span>first1 <span class="sy2">*</span> <span class="sy2">*</span>first2</span></span> &#20462;&#25913;&#23427;&#65292;&#20877;&#20197;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp">acc <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span> <span class="sy2">+</span> <span class="sy2">*</span><span class="br0">(</span>first1<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span> <span class="sy2">*</span> <span class="sy2">*</span><span class="br0">(</span>first2<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span></span></span> &#20462;&#25913;&#23427;&#65292;&#20197;&#27492;&#31867;&#25512;</p>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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&#30452;&#33267;&#25269;&#36798; <code>last1</code> &#12290;&#23545;&#20110; + &#19982; * &#30340;&#20869;&#24314;&#21547;&#20041;&#65292;&#27492;&#31639;&#27861;&#35745;&#31639;&#20108;&#20010;&#33539;&#22260;&#30340;&#20869;&#31215;&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#20197;&#21021;&#20540; <code>init</code> &#21021;&#22987;&#21270;&#31215;&#32047;&#22120; <code>acc</code> &#65292;&#28982;&#21518;
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<p>&#20197;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp">acc <span class="sy1">=</span> op1<span class="br0">(</span>acc, op2<span class="br0">(</span><span class="sy2">*</span>first1, <span class="sy2">*</span>first2<span class="br0">)</span><span class="br0">)</span></span></span> &#20462;&#25913;&#23427;&#65292;&#20877;&#20197;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp">acc <span class="sy1">=</span> op1<span class="br0">(</span>acc, op2<span class="br0">(</span><span class="sy2">*</span><span class="br0">(</span>first1<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span>, <span class="sy2">*</span><span class="br0">(</span>first2<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span><span class="br0">)</span><span class="br0">)</span></span></span> &#20462;&#25913;&#23427;&#65292;&#20197;&#27492;&#31867;&#25512;</p>
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<td><span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
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<tr class="t-rev t-since-cxx20">
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<p>&#20197;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp">acc <span class="sy1">=</span> op1<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span>, op2<span class="br0">(</span><span class="sy2">*</span>first1, <span class="sy2">*</span>first2<span class="br0">)</span><span class="br0">)</span></span></span> &#20462;&#25913;&#23427;&#65292;&#20877;&#20197;&#34920;&#36798;&#24335; <span class="t-c"><span class="mw-geshi cpp source-cpp">acc <span class="sy1">=</span> op1<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span>, op2<span class="br0">(</span><span class="sy2">*</span><span class="br0">(</span>first1<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span>, <span class="sy2">*</span><span class="br0">(</span>first2<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span><span class="br0">)</span><span class="br0">)</span></span></span> &#20462;&#25913;&#23427;&#65292;&#20197;&#27492;&#31867;&#25512;</p>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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</table>
&#30452;&#33267;&#25269;&#36798; <code>last1</code> &#12290;</div>
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<p><code>op1</code> &#25110; <code>op2</code> &#24517;&#39035;&#26080;&#21103;&#20316;&#29992;&#12290;</p>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 &#21069;)</span></td>
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<p><code>op1</code> &#25110; <code>op2</code> &#24517;&#39035;&#19981;&#38750;&#27861;&#21270;&#25152;&#28041;&#21450;&#33539;&#22260;&#30340;&#20219;&#20309;&#36845;&#20195;&#22120;&#65292;&#21547;&#23614;&#36845;&#20195;&#22120;&#25110;&#20462;&#25913;&#35813;&#33539;&#22260;&#30340;&#20219;&#20309;&#20803;&#32032;&#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=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>first1, last1</td>
<td>-</td>
<td>&#20803;&#32032;&#33539;&#22260;</td>
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<tr class="t-par">
<td>first2</td>
<td>-</td>
<td>&#31532;&#20108;&#20010;&#20803;&#32032;&#33539;&#22260;&#30340;&#36215;&#22987;</td>
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<tr class="t-par">
<td>init</td>
<td>-</td>
<td>&#31215;&#30340;&#21644;&#30340;&#21021;&#20540;</td>
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<td>op1</td>
<td>-</td>
<td>&#34987;&#20351;&#29992;&#30340;&#20108;&#20803;&#20989;&#25968;&#23545;&#35937;&#12290;&#27492;&ldquo;&#21644;&rdquo;&#20989;&#25968;&#25509;&#25910; op2 &#25152;&#36820;&#22238;&#30340;&#20540;&#21644;&#24403;&#21069;&#31215;&#32047;&#22120;&#30340;&#20540;&#65292;&#24182;&#20135;&#29983;&#23384;&#20648;&#20110;&#31215;&#32047;&#22120;&#30340;&#26032;&#20540;&#12290;<br />
<p>&#35813;&#20989;&#25968;&#30340;&#31614;&#21517;&#24212;&#24403;&#31561;&#20215;&#20110;&#65306;</p>
<p><span class="t-cc"><span class="mw-geshi cpp source-cpp">&nbsp;Ret fun<span class="br0">(</span><span class="kw4">const</span> Type1 <span class="sy3">&amp;</span>a, <span class="kw4">const</span> Type2 <span class="sy3">&amp;</span>b<span class="br0">)</span><span class="sy4">;</span></span></span></p>
<p>&#31614;&#21517;&#20013;&#24182;&#19981;&#38656;&#35201;&#26377; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <span class="sy3">&amp;</span></span></span>&#12290;<br />
&#31867;&#22411; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1</span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type2</span></span> &#24517;&#39035;&#20351;&#24471; <span class="t-c"><span class="mw-geshi cpp source-cpp">T</span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type3</span></span> &#31867;&#22411;&#30340;&#23545;&#35937;&#21508;&#33021;&#38544;&#24335;&#36716;&#25442;&#25104; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1</span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type2</span></span> &#12290; &#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">T</span></span> &#31867;&#22411;&#23545;&#35937;&#33021;&#34987;&#36171; <span class="t-c"><span class="mw-geshi cpp source-cpp">Ret</span></span> &#31867;&#22411;&#20540;&#12290; &#8203;</p>
</td>
</tr>
<tr class="t-par">
<td>op2</td>
<td>-</td>
<td>&#34987;&#20351;&#29992;&#30340;&#20108;&#20803;&#20989;&#25968;&#23545;&#35937;&#12290;&#27492;&ldquo;&#31215;&rdquo;&#20989;&#25968;&#20174;&#27599;&#20010;&#33539;&#22260;&#25509;&#25910;&#19968;&#20010;&#20540;&#24182;&#20135;&#29983;&#26032;&#20540;&#12290;<br />
<p>&#35813;&#20989;&#25968;&#30340;&#31614;&#21517;&#24212;&#24403;&#31561;&#20215;&#20110;&#65306;</p>
<p><span class="t-cc"><span class="mw-geshi cpp source-cpp">&nbsp;Ret fun<span class="br0">(</span><span class="kw4">const</span> Type1 <span class="sy3">&amp;</span>a, <span class="kw4">const</span> Type2 <span class="sy3">&amp;</span>b<span class="br0">)</span><span class="sy4">;</span></span></span></p>
<p>&#31614;&#21517;&#20013;&#24182;&#19981;&#38656;&#35201;&#26377; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <span class="sy3">&amp;</span></span></span>&#12290;<br />
&#31867;&#22411; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1</span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type2</span></span> &#24517;&#39035;&#20351;&#24471; <span class="t-c"><span class="mw-geshi cpp source-cpp">InputIt1</span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp">InputIt2</span></span> &#31867;&#22411;&#30340;&#23545;&#35937;&#22312;&#35299;&#24341;&#29992;&#21518;&#20998;&#21035;&#33021;&#38544;&#24335;&#36716;&#25442;&#21040; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1</span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type2</span></span> &#12290; &#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">Type3</span></span> &#31867;&#22411;&#23545;&#35937;&#33021;&#34987;&#36171; <span class="t-c"><span class="mw-geshi cpp source-cpp">Ret</span></span> &#31867;&#22411;&#20540;&#12290; &#8203;</p>
</td>
</tr>
<tr class="t-par-hitem">
<td colspan="3">&#31867;&#22411;&#35201;&#27714;</td>
</tr>
<tr class="t-par-req">
<td colspan="3">-
<div class="spacer"></div>
<code>InputIt1, InputIt2</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">&#32769;&#24335;&#36755;&#20837;&#36845;&#20195;&#22120;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LegacyInputIterator)</span></a> &#30340;&#35201;&#27714;&#12290;</td>
</tr>
<tr class="t-par-req">
<td colspan="3">-
<div class="spacer"></div>
<code>ForwardIt1, ForwardIt2</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>
</tr>
<tr class="t-par-req">
<td colspan="3">-
<div class="spacer"></div>
<code>T</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-CopyAssignable.html"><span style="font-style:italic">&#21487;&#22797;&#21046;&#36171;&#20540;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(CopyAssignable)</span></a> &#21644; <a href="cpp-named_req-CopyConstructible.html"><span style="font-style:italic">&#21487;&#22797;&#21046;&#26500;&#36896;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(CopyConstructible)</span></a> &#30340;&#35201;&#27714;&#12290;</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#19978;&#36848; <code>acc</code> &#30340;&#26368;&#32456;&#20540;&#12290;</p>
<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>
<table class="eq-fun-cpp-table">
<tr>
<th>&#29256;&#26412;&#19968;</th>
</tr>
<tr>
<td>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="cpp source-cpp">
<pre class="de1"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> InputIt1, <span class="kw1">class</span> InputIt2, <span class="kw1">class</span> T<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="co1">// C++20 &#36215;</span>
T inner_product<span class="br0">(</span>InputIt1 first1, InputIt1 last1,
InputIt2 first2, T init<span class="br0">)</span>
<span class="br0">{</span>
<span class="kw1">while</span> <span class="br0">(</span>first1 <span class="sy3">!</span><span class="sy1">=</span> last1<span class="br0">)</span> <span class="br0">{</span>
init <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>init<span class="br0">)</span> <span class="sy2">+</span> <span class="sy2">*</span>first1 <span class="sy2">*</span> <span class="sy2">*</span>first2<span class="sy4">;</span> <span class="co1">// C++20 &#36215;&#26377; std::move</span>
<span class="sy2">++</span>first1<span class="sy4">;</span>
<span class="sy2">++</span>first2<span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">return</span> init<span class="sy4">;</span>
<span class="br0">}</span></pre></div>
</div>
</td>
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<tr>
<th>&#29256;&#26412;&#20108;</th>
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<td>
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<pre class="de1"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> InputIt1, <span class="kw1">class</span> InputIt2,
<span class="kw1">class</span> T,
<span class="kw1">class</span> BinaryOperation1, <span class="kw1">class</span> BinaryOperation2<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="co1">// C++20 &#36215;</span>
T inner_product<span class="br0">(</span>InputIt1 first1, InputIt1 last1,
InputIt2 first2, T init,
BinaryOperation1 op1,
BinaryOperation2 op2<span class="br0">)</span>
<span class="br0">{</span>
<span class="kw1">while</span> <span class="br0">(</span>first1 <span class="sy3">!</span><span class="sy1">=</span> last1<span class="br0">)</span> <span class="br0">{</span>
init <span class="sy1">=</span> op1<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>init<span class="br0">)</span>, op2<span class="br0">(</span><span class="sy2">*</span>first1, <span class="sy2">*</span>first2<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// C++20 &#36215;&#26377; std::move</span>
<span class="sy2">++</span>first1<span class="sy4">;</span>
<span class="sy2">++</span>first2<span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">return</span> init<span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">&#27880;&#24847;</span></h3>
<p>&#27492;&#31639;&#27861;&#30340;&#21487;&#24182;&#34892;&#29256;&#26412; <span class="t-lc"><a href="cpp-algorithm-transform_reduce.html">std::transform_reduce</a></span> &#35201;&#27714; <code>op1</code> &#19982; <code>op2</code> &#21487;&#20132;&#25442;&#24182;&#21487;&#32467;&#21512;&#65292;&#20294; <code>std::inner_product</code> &#19981;&#20316;&#36825;&#31181;&#35201;&#27714;&#65292;&#19988;&#22987;&#32456;&#20197;&#32473;&#23450;&#39034;&#24207;&#36827;&#34892;&#25805;&#20316;&#12290;</p>
<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>
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<div class="cpp source-cpp">
<pre class="de1"><span class="co2">#include &lt;numeric&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;vector&gt;</span>
<span class="co2">#include &lt;functional&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> a<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="br0">}</span><span class="sy4">;</span>
<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> b<span class="br0">{</span><span class="nu0">5</span>, <span class="nu0">4</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">1</span><span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">int</span> r1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">inner_product</span><span class="br0">(</span>a.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, a.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, b.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, <span class="nu0">0</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;Inner product of a and b: &quot;</span> <span class="sy1">&lt;&lt;</span> r1 <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="kw4">int</span> r2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">inner_product</span><span class="br0">(</span>a.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, a.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, b.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, <span class="nu0">0</span>,
<a href="cpp-utility-functional-plus.html"><span class="kw1029">std::<span class="me2">plus</span></span></a><span class="sy1">&lt;&gt;</span><span class="br0">(</span><span class="br0">)</span>, <a href="cpp-utility-functional-equal_to.html"><span class="kw1035">std::<span class="me2">equal_to</span></span></a><span class="sy1">&lt;&gt;</span><span class="br0">(</span><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">&quot;Number of pairwise matches between a and b: &quot;</span> <span class="sy1">&lt;&lt;</span> r2 <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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<div class="text source-text">
<pre class="de1">Inner product of a and b: 21
Number of pairwise matches between a and b: 2</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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<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-transform_reduce.html"><span class="t-lines"><span>transform_reduce</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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<td>&#24212;&#29992;&#19968;&#20010;&#20989;&#25968;&#23545;&#35937;&#65292;&#28982;&#21518;&#20197;&#20081;&#24207;&#35268;&#32422;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-accumulate.html"><span class="t-lines"><span>accumulate</span></span></a></div>
</div>
</td>
<td>&#23545;&#19968;&#20010;&#33539;&#22260;&#20869;&#30340;&#20803;&#32032;&#27714;&#21644;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
</tr>
<tr class="t-dsc">
<td>
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<div><a href="cpp-algorithm-partial_sum.html"><span class="t-lines"><span>partial_sum</span></span></a></div>
</div>
</td>
<td>&#35745;&#31639;&#33539;&#22260;&#20869;&#20803;&#32032;&#30340;&#37096;&#20998;&#21644;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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