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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>clamp</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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<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><br />
<span class="kw4">constexpr</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> clamp<span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> v, <span class="kw4">const</span> T<span class="sy3">&amp;</span> lo, <span class="kw4">const</span> T<span class="sy3">&amp;</span> hi <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
<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"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> T, <span class="kw1">class</span> Compare<span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> clamp<span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> v, <span class="kw4">const</span> T<span class="sy3">&amp;</span> lo, <span class="kw4">const</span> T<span class="sy3">&amp;</span> hi, Compare comp <span class="br0">)</span><span class="sy4">;</span></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>v</code> &#23567;&#20110; <code>lo</code> &#65292;&#21017;&#36820;&#22238; <code>lo</code> &#65307;&#33509; <code>v</code> &#22823;&#20110; <code>hi</code> &#65292;&#21017;&#36820;&#22238; <code>hi</code> &#65307;&#21542;&#21017;&#36820;&#22238; <code>v</code> &#12290;&#20351;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy1">&lt;</span></span></span> &#27604;&#36739;&#20540;&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#21516; <span class="t-v">(1)</span> &#65292;&#19981;&#36807;&#20351;&#29992; <code>comp</code> &#27604;&#36739;&#20540;&#12290;</div>
<p>&#33509; <code>lo</code> &#30340;&#20540;&#22823;&#20110; <code>hi</code> &#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>v</td>
<td>-</td>
<td>&#35201;&#22841;&#20303;&#30340;&#20540;</td>
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<td>lo,hi</td>
<td>-</td>
<td>&#22841; <code>v</code> &#30340;&#36793;&#30028;</td>
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<td>comp</td>
<td>-</td>
<td>&#27604;&#36739;&#20989;&#25968;&#23545;&#35937;&#65288;&#21363;&#28385;&#36275;<a href="cpp-named_req-Compare.html"><span style="font-style:italic">&#27604;&#36739;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Compare)</span></a> &#35201;&#27714;&#30340;&#23545;&#35937;&#65289;&#65292;&#33509; <code>lo</code> <i>&#23567;&#20110;</i> <code>v</code> &#19988; <code>v</code> <i>&#23567;&#20110;</i> <code>hi</code>&#65292;&#21017;&#36820;&#22238; &#8203;<span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#12290;<br />
<p>&#27604;&#36739;&#20989;&#25968;&#30340;&#31614;&#21517;&#24212;&#31561;&#20215;&#20110;&#22914;&#19979;&#65306;</p>
<p><span class="t-cc"><span class="mw-geshi cpp source-cpp">&nbsp;<span class="kw4">bool</span> cmp<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>&#34429;&#28982;&#31614;&#21517;&#19981;&#24517;&#26377; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <span class="sy3">&amp;</span></span></span> &#65292;&#20989;&#25968;&#20063;&#19981;&#33021;&#20462;&#25913;&#20256;&#36882;&#32473;&#23427;&#30340;&#23545;&#35937;&#65292;&#32780;&#19988;&#24517;&#39035;&#25509;&#21463;&#65288;&#21487;&#20026; const &#30340;&#65289;&#31867;&#22411; <code>Type1</code> &#19982; <code>Type2</code> &#30340;&#20540;&#65292;&#26080;&#20851;&#20046;<a href="cpp-language-value_category.html">&#20540;&#31867;&#21035;</a>&#65288;&#20174;&#32780;&#19981;&#20801;&#35768; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1 <span class="sy3">&amp;</span></span></span> <span class="t-rev-inl t-since-cxx11"><span>&#65292;&#20134;&#19981;&#20801;&#35768; <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1</span></span> &#65292;&#38500;&#38750; <code>Type1</code> &#30340;&#31227;&#21160;&#31561;&#20215;&#20110;&#22797;&#21046;</span> <span><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></span></span>&#65289;&#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> &#31867;&#22411;&#30340;&#23545;&#35937;&#33021;&#38544;&#24335;&#36716;&#25442;&#21040;&#36825;&#20004;&#20010;&#31867;&#22411;&#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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&#20026;&#20351;&#29992;&#37325;&#36733; (1) &#65292; <code>T</code> &#24517;&#39035;&#28385;&#36275;<a href="cpp-named_req-LessThanComparable.html"><span style="font-style:italic">&#21487;&#23567;&#20110;&#27604;&#36739;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(LessThanComparable)</span></a> &#30340;&#35201;&#27714;&#12290;&#28982;&#32780;&#33509;&#36991;&#20813;&#20102; <code>NaN</code> &#65292;&#21017; <code>T</code> &#33021;&#20026;&#28014;&#28857;&#31867;&#22411;&#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>
<p>&#33509; <code>v</code> &#23567;&#20110; <code>lo</code> &#21040;&#21017;&#20026; <code>lo</code> &#30340;&#24341;&#29992;&#65292;&#33509; <code>hi</code> &#23567;&#20110; <code>v</code> &#21017;&#20026;&#21040; <code>hi</code> &#30340;&#24341;&#29992;&#65292;&#21542;&#21017;&#20026;&#21040; <code>v</code> &#30340;&#24341;&#29992;&#12290;</p>
<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">&#22797;&#26434;&#24230;</span></h3>
<p>&#33267;&#22810;&#20108;&#27425;&#27604;&#36739;</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>
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<th>&#29256;&#26412;&#19968;</th>
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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> T<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> clamp<span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> v, <span class="kw4">const</span> T<span class="sy3">&amp;</span> lo, <span class="kw4">const</span> T<span class="sy3">&amp;</span> hi <span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span> <span class="sy3">!</span><span class="br0">(</span>hi <span class="sy1">&lt;</span> lo<span class="br0">)</span> <span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">return</span> v <span class="sy1">&lt;</span> lo <span class="sy4">?</span> lo <span class="sy4">:</span> hi <span class="sy1">&lt;</span> v <span class="sy4">?</span> hi <span class="sy4">:</span> v<span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<tr>
<th>&#29256;&#26412;&#20108;</th>
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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> T, <span class="kw1">class</span> Compare<span class="sy1">&gt;</span>
<span class="kw4">constexpr</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> clamp<span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> v, <span class="kw4">const</span> T<span class="sy3">&amp;</span> lo, <span class="kw4">const</span> T<span class="sy3">&amp;</span> hi, Compare comp <span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span> <span class="sy3">!</span>comp<span class="br0">(</span>hi, lo<span class="br0">)</span> <span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">return</span> comp<span class="br0">(</span>v, lo<span class="br0">)</span> <span class="sy4">?</span> lo <span class="sy4">:</span> comp<span class="br0">(</span>hi, v<span class="br0">)</span> <span class="sy4">?</span> hi <span class="sy4">:</span> v<span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<div class="t-template-editlink" style=""></div>
&#33509;&#21442;&#25968;&#20043;&#19968;&#26159;&#20020;&#26102;&#37327;&#65292;&#32780;&#35813;&#21442;&#25968;&#34987;&#36820;&#22238;&#65292;&#21017;&#20197;&#24341;&#29992;&#25429;&#33719; <code>std::clamp</code> &#30340;&#32467;&#26524;&#20250;&#20135;&#29983;&#19968;&#20010;&#24748;&#22402;&#24341;&#29992;&#65306;
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="cpp source-cpp">
<pre class="de1"><span class="kw4">int</span> n <span class="sy1">=</span> <span class="sy2">-</span><span class="nu0">1</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">int</span><span class="sy3">&amp;</span> r <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">clamp</span><span class="br0">(</span>n, <span class="nu0">0</span>, <span class="nu0">255</span><span class="br0">)</span><span class="sy4">;</span>
<span class="co1">// r &#24748;&#22402;</span></pre></div>
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<p>&#33509; <code>v</code> &#19982;&#36793;&#30028;&#20043;&#19968;&#27604;&#36739;&#30456;&#31561;&#65292;&#21017;&#36820;&#22238;&#21040; <code>v</code> &#30340;&#24341;&#29992;&#65292;&#32780;&#38750;&#21040;&#36793;&#30028;&#32773;&#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>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="cpp source-cpp">
<pre class="de1"><span class="co2">#include &lt;cstdint&gt;</span>
<span class="co2">#include &lt;algorithm&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;iomanip&gt;</span>
<span class="co2">#include &lt;random&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> g<span class="br0">(</span><a href="cpp-numeric-random-random_device.html"><span class="kw1486">std::<span class="me2">random_device</span></span></a><span class="br0">{</span><span class="br0">}</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-numeric-random-uniform_int_distribution.html"><span class="kw1502">std::<span class="me2">uniform_int_distribution</span></span></a><span class="sy1">&lt;&gt;</span> d<span class="br0">(</span><span class="sy2">-</span><span class="nu0">300</span>, <span class="nu0">300</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; raw clamped to int8_t clamped to uint8_t<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="kw1">for</span><span class="br0">(</span><span class="kw4">int</span> n <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> n <span class="sy1">&lt;</span> <span class="nu0">5</span><span class="sy4">;</span> <span class="sy2">++</span>n<span class="br0">)</span> <span class="br0">{</span>
<span class="kw4">int</span> v <span class="sy1">=</span> d<span class="br0">(</span>g<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> <a href="cpp-io-manip-setw.html"><span class="kw1796">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">4</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> v
<span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-setw.html"><span class="kw1796">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">20</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> std<span class="sy4">::</span><span class="me2">clamp</span><span class="br0">(</span>v, <a href="cpp-types-integer.html"><span class="kw134">INT8_MIN</span></a>, <a href="cpp-types-integer.html"><span class="kw148">INT8_MAX</span></a><span class="br0">)</span>
<span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-setw.html"><span class="kw1796">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">21</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> std<span class="sy4">::</span><span class="me2">clamp</span><span class="br0">(</span>v, <span class="nu0">0</span>, <a href="cpp-types-integer.html"><span class="kw162">UINT8_MAX</span></a><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="br0">}</span></pre></div>
</div>
<p>&#21487;&#33021;&#30340;&#36755;&#20986;&#65306;</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="text source-text">
<pre class="de1">.raw clamped to int8_t clamped to uint8_t
168 127 168
128 127 128
-137 -128 0
40 40 40
-66 -66 0</pre></div>
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<p><br /></p>
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
<table class="t-dsc-begin">
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-algorithm-min.html"><span class="t-lines"><span>min</span></span></a></div>
</div>
</td>
<td>&#36820;&#22238;&#21508;&#32473;&#23450;&#20540;&#20013;&#30340;&#36739;&#23567;&#32773;<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-max.html"><span class="t-lines"><span>max</span></span></a></div>
</div>
</td>
<td>&#36820;&#22238;&#21508;&#32473;&#23450;&#20540;&#20013;&#30340;&#36739;&#22823;&#32773;<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-utility-in_range.html"><span class="t-lines"><span>in_range</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>&#26816;&#26597;&#25972;&#25968;&#20540;&#26159;&#21542;&#22312;&#32473;&#23450;&#25972;&#25968;&#31867;&#22411;&#30340;&#33539;&#22260;&#20869;<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-clamp.html"><span class="t-lines"><span>ranges::clamp</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>&#22312;&#19968;&#23545;&#36793;&#30028;&#20540;&#38388;&#22841;&#19968;&#20010;&#20540;<br />
<span class="t-mark">(niebloid)</span></td>
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</table>
</div>
<div class="visualClear"></div>
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