122 lines
9.5 KiB
HTML
122 lines
9.5 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::feraiseexcept</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_numeric_fenv_feraiseexcept skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>feraiseexcept</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-numeric.html">numeric</a>‎ | <a href="cpp-numeric-fenv.html">fenv</a></span></div>
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<table class="t-dcl-begin">
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<td>
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<div>定义于头文件 <code><a href="cpp-header-cfenv.html"><cfenv></a></code></div>
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<td></td>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> feraiseexcept<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>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<tr class="t-dcl-sep">
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<td></td>
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<p>试图引发所有列于 <code>excepts</code> （<a href="cpp-numeric-fenv-FE_exceptions.html">浮点异常宏</a>的逐位或）的浮点异常。若异常之一是 <span class="t-lc"><a href="cpp-numeric-fenv-FE_exceptions.html">FE_OVERFLOW</a></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1465">FE_UNDERFLOW</span></a></span></span> ，则此函数还会再引发 <span class="t-lc"><a href="cpp-numeric-fenv-FE_exceptions.html">FE_INEXACT</a></span> 。引发异常所用的顺序是未指定的，除了 <span class="t-lc"><a href="cpp-numeric-fenv-FE_exceptions.html">FE_OVERFLOW</a></span> 和 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1465">FE_UNDERFLOW</span></a></span></span> 始终先于 <span class="t-lc"><a href="cpp-numeric-fenv-FE_exceptions.html">FE_INEXACT</a></span> 引发。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>excepts</td>
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<td>-</td>
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<td>列出要引发的异常标志的位掩码</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>若已引发所有列出的异常则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span> ，否则为非零值。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <cfenv></span>
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<span class="co2">#pragma STDC FENV_ACCESS ON</span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<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>
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<span class="kw4">int</span> r <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">feraiseexcept</span><span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1465">FE_UNDERFLOW</span></a> <span class="sy3">|</span> <a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1461">FE_DIVBYZERO</span></a><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Raising divbyzero and underflow simultaneously "</span>
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<span class="sy1"><<</span> <span class="br0">(</span>r<span class="sy4">?</span><span class="st0">"fails"</span><span class="sy4">:</span><span class="st0">"succeeds"</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">" and results in<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw4">int</span> e <span class="sy1">=</span> <a href="cpp-numeric-fenv-fetestexcept.html"><span class="kw1451">std::<span class="me2">fetestexcept</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>
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<span class="kw1">if</span> <span class="br0">(</span>e <span class="sy3">&</span> <a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1461">FE_DIVBYZERO</span></a><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"division by zero<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">if</span> <span class="br0">(</span>e <span class="sy3">&</span> <a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1462">FE_INEXACT</span></a><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"inexact<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">if</span> <span class="br0">(</span>e <span class="sy3">&</span> <a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1463">FE_INVALID</span></a><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"invalid<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">if</span> <span class="br0">(</span>e <span class="sy3">&</span> <a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1465">FE_UNDERFLOW</span></a><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"underflow<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">if</span> <span class="br0">(</span>e <span class="sy3">&</span> <a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1464">FE_OVERFLOW</span></a><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"overflow<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">Raising divbyzero and underflow simultaneously succeeds and results in
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division by zero
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underflow</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-fenv-feclearexcept.html"><span class="t-lines"><span>feclearexcept</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>清除指定的浮点状态标志<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-fenv-fetestexcept.html"><span class="t-lines"><span>fetestexcept</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>确定设置了哪个指定的浮点状态标志<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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