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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>fetestexcept</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> fetestexcept<span class="br0">(</span> <span class="kw4">int</span> excepts <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></td>
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<p>&#30830;&#23450;&#24403;&#21069;&#35774;&#23450;&#20102;&#21738;&#20010;&#28014;&#28857;&#24322;&#24120;&#30340;&#25351;&#23450;&#23376;&#38598;&#12290;&#21442;&#25968; <code>excepts</code> &#26159;<a href="cpp-numeric-fenv-FE_exceptions.html">&#28014;&#28857;&#24322;&#24120;&#23439;</a>&#30340;&#36880;&#20301;&#25110;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>excepts</td>
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<td>&#21015;&#20986;&#35201;&#27979;&#35797;&#30340;&#24322;&#24120;&#26631;&#24535;&#30340;&#20301;&#25513;&#30721;</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>&#21253;&#21547;&#20110; <code>excepts</code> &#32780;&#19988;&#23545;&#24212;&#20110;&#24403;&#21069;&#35774;&#32622;&#30340;&#28014;&#28857;&#24322;&#24120;&#20013;&#30340;&#28014;&#28857;&#24322;&#24120;&#23439;&#30340;&#36880;&#20301;&#25110;&#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;cfenv&gt;</span>
<span class="co2">#include &lt;cmath&gt;</span>
<span class="co2">#pragma STDC FENV_ACCESS ON</span>
<span class="kw4">volatile</span> <span class="kw4">double</span> zero <span class="sy1">=</span> <span class="nu16">0.0</span><span class="sy4">;</span> <span class="co1">// &#25903;&#25345; FENV_ACCESS &#22788;&#19981;&#38656;&#35201; volatile</span>
<span class="kw4">volatile</span> <span class="kw4">double</span> one <span class="sy1">=</span> <span class="nu16">1.0</span><span class="sy4">;</span> <span class="co1">// &#25903;&#25345; FENV_ACCESS &#22788;&#19981;&#38656;&#35201; volatile</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-numeric-fenv-feclearexcept.html"><span class="kw1450">std::<span class="me2">feclearexcept</span></span></a><span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1460">FE_ALL_EXCEPT</span></a><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;1.0/0.0 = &quot;</span> <span class="sy1">&lt;&lt;</span> <span class="nu16">1.0</span> <span class="sy2">/</span> zero <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="kw1">if</span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">fetestexcept</span><span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1461">FE_DIVBYZERO</span></a><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</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;division by zero reported<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="br0">}</span> <span class="kw1">else</span> <span class="br0">{</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;divsion by zero not reported<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="br0">}</span>
<a href="cpp-numeric-fenv-feclearexcept.html"><span class="kw1450">std::<span class="me2">feclearexcept</span></span></a><span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1460">FE_ALL_EXCEPT</span></a><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;1.0/10 = &quot;</span> <span class="sy1">&lt;&lt;</span> one<span class="sy2">/</span><span class="nu0">10</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">if</span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">fetestexcept</span><span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1462">FE_INEXACT</span></a><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</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;inexact result reported<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="br0">}</span> <span class="kw1">else</span> <span class="br0">{</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;inexact result not reported<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="br0">}</span>
<a href="cpp-numeric-fenv-feclearexcept.html"><span class="kw1450">std::<span class="me2">feclearexcept</span></span></a><span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1460">FE_ALL_EXCEPT</span></a><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;sqrt(-1) = &quot;</span> <span class="sy1">&lt;&lt;</span> <a href="cpp-numeric-math-sqrt.html"><span class="kw1329">std::<span class="me2">sqrt</span></span></a><span class="br0">(</span><span class="sy2">-</span><span class="nu0">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="sy4">;</span>
<span class="kw1">if</span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">fetestexcept</span><span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1463">FE_INVALID</span></a><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</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;invalid result reported<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="br0">}</span> <span class="kw1">else</span> <span class="br0">{</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;invalid result not reported<span class="es1">\n</span>&quot;</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
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<pre class="de1">1.0/0.0 = inf
division by zero reported
1.0/10 = 0.1
inexact result reported
sqrt(-1) = -nan
invalid result reported</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-fenv-feclearexcept.html"><span class="t-lines"><span>feclearexcept</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>&#28165;&#38500;&#25351;&#23450;&#30340;&#28014;&#28857;&#29366;&#24577;&#26631;&#24535;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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