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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>fegetround, <span style="font-size:0.7em; line-height:130%">std::</span>fesetround</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-fenv.html">fenv</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-cfenv.html">&lt;cfenv&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fesetround<span class="br0">(</span> <span class="kw4">int</span> round <span class="br0">)</span></span></div>
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<td>(1)</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fegetround<span class="br0">(</span><span class="br0">)</span></span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<p>&#31649;&#29702;&#28014;&#28857;&#33293;&#20837;&#26041;&#21521;&#12290;</p>
<div class="t-li1"><span class="t-li">1)</span> &#35797;&#22270;&#24314;&#31435;&#31561;&#20110;&#21442;&#25968; <code>round</code> &#30340;&#28014;&#28857;&#33293;&#20837;&#26041;&#21521;&#65292;&#26399;&#24453;&#21442;&#25968;&#20026;<a href="cpp-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#20043;&#19968;&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#36820;&#22238;&#23545;&#24212;&#24403;&#21069;&#33293;&#20837;&#26041;&#21521;&#30340;<a href="cpp-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#12290;</div>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>round</td>
<td>-</td>
<td>&#33293;&#20837;&#26041;&#21521;&#65292;<a href="cpp-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#20043;&#19968;</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>1) &#25104;&#21151;&#26102;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp">&#8203;<span class="nu0">0</span>&#8203;</span></span> &#65292;&#21542;&#21017;&#20026;&#38750;&#38646;&#12290;</p>
<p>2) &#25551;&#36848;&#24403;&#21069;&#33293;&#20837;&#26041;&#21521;&#30340;<a href="cpp-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#65292;&#25110;&#33509;&#19981;&#33021;&#30830;&#23450;&#26041;&#21521;&#21017;&#20026;&#36127;&#20540;</p>
<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">&#27880;&#24847;</span></h3>
<p>&#24403;&#21069;&#33293;&#20837;&#26041;&#21521;&#21453;&#26144;&#26368;&#36817;&#30340; <code>fesetround</code> &#30340;&#25928;&#26524;&#65292;&#20134;&#33021;&#20197; <span class="t-lc"><a href="cpp-types-climits-FLT_ROUNDS.html">FLT_ROUNDS</a></span> &#26597;&#35810;&#12290;</p>
<p>&#33293;&#20837;&#30340;&#25928;&#26524;&#35265;<a href="cpp-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-template-editlink" style=""></div>
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<pre class="de1"><span class="co2">#include &lt;cmath&gt;</span>
<span class="co2">#include &lt;cfenv&gt;</span>
<span class="co2">#include &lt;iostream&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="co2">#pragma STDC FENV_ACCESS ON</span>
std<span class="sy4">::</span><span class="me2">fesetround</span><span class="br0">(</span><a href="cpp-numeric-fenv-FE_round.html"><span class="kw1465">FE_DOWNWARD</span></a><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1756">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;rounding using FE_DOWNWARD: <span class="es1">\n</span>&quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-fixed.html"><span class="kw1782">std::<span class="me2">fixed</span></span></a>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 12.0 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">12.0</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 12.1 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">12.1</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;-12.1 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="sy2">-</span><span class="nu16">12.1</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 12.5 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">12.5</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 12.9 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">12.9</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;-12.9 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="sy2">-</span><span class="nu16">12.9</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 13.0 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">13.0</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>
std<span class="sy4">::</span><span class="me2">fesetround</span><span class="br0">(</span><a href="cpp-numeric-fenv-FE_round.html"><span class="kw1466">FE_TONEAREST</span></a><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1756">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;rounding using FE_TONEAREST: <span class="es1">\n</span>&quot;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 12.0 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">12.0</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 12.1 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">12.1</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;-12.1 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="sy2">-</span><span class="nu16">12.1</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 12.5 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">12.5</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 12.9 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">12.9</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;-12.9 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="sy2">-</span><span class="nu16">12.9</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; 13.0 -&gt; &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-nearbyint.html"><span class="kw1356">std::<span class="me2">nearbyint</span></span></a><span class="br0">(</span><span class="nu16">13.0</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></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
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<div class="text source-text">
<pre class="de1">rounding using FE_DOWNWARD:
12.0 -&gt; 12.000000
12.1 -&gt; 12.000000
-12.1 -&gt; -13.000000
12.5 -&gt; 12.000000
12.9 -&gt; 12.000000
-12.9 -&gt; -13.000000
13.0 -&gt; 13.000000
rounding using FE_TONEAREST:
12.0 -&gt; 12.000000
12.1 -&gt; 12.000000
-12.1 -&gt; -12.000000
12.5 -&gt; 12.000000
12.9 -&gt; 13.000000
-12.9 -&gt; -13.000000
13.0 -&gt; 13.000000</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-numeric-math-nearbyint.html"><span class="t-lines"><span>nearbyint</span><span>nearbyintf</span><span>nearbyintl</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>&#20351;&#29992;&#24403;&#21069;&#33293;&#20837;&#27169;&#24335;&#30340;&#26368;&#25509;&#36817;&#25972;&#25968;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-numeric-math-rint.html"><span class="t-lines"><span>rint</span><span>rintf</span><span>rintl</span><span>lrint</span><span>lrintf</span><span>lrintl</span><span>llrint</span><span>llrintf</span><span>llrintl</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>&#20351;&#29992;&#24403;&#21069;&#33293;&#20837;&#27169;&#24335;&#30340;&#26368;&#25509;&#36817;&#25972;&#25968;<br />
&#33509;&#32467;&#26524;&#26377;&#21035;&#21017;&#26377;&#24322;&#24120;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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