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151 lines
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<title>feraiseexcept</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_numeric_fenv_feraiseexcept skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading">feraiseexcept</h1>
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<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-numeric.html">numeric</a>‎ | <a href="c-numeric-fenv.html">fenv</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<div>定义于头文件 <code><fenv.h></code></div>
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<td></td>
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<td></td>
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<div><span class="mw-geshi c source-c"><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 class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-c99">(C99 起)</span></td>
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<p>尝试引发所有列于 <code>excepts</code> (<a href="c-numeric-fenv-FE_exceptions.html">浮点异常宏</a>的逐位或)的浮点异常。若异常之一为 <span class="t-lc"><a href="c-numeric-fenv-FE_exceptions.html">FE_OVERFLOW</a></span> 或 <span class="t-c"><span class="mw-geshi c source-c"><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw733">FE_UNDERFLOW</span></a></span></span> ,则此函数可以额外引发 <span class="t-lc"><a href="c-numeric-fenv-FE_exceptions.html">FE_INEXACT</a></span> 。异常的引发顺序未指定,除了 <span class="t-lc"><a href="c-numeric-fenv-FE_exceptions.html">FE_OVERFLOW</a></span> 和 <span class="t-c"><span class="mw-geshi c source-c"><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw733">FE_UNDERFLOW</span></a></span></span> 一定先于 <span class="t-lc"><a href="c-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>列出所有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>若引发了所有列出的异常,则返回 <span class="t-c"><span class="mw-geshi c source-c">​<span class="nu0">0</span>​</span></span> ,否则返回非零值。</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="c source-c">
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<pre class="de1"><span class="co2">#include <stdio.h></span>
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<span class="co2">#include <fenv.h></span>
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<span class="co2">#pragma STDC FENV_ACCESS ON</span>
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<span class="kw4">void</span> show_fe_exceptions<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"current exceptions raised: "</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span><a href="c-numeric-fenv-fetestexcept.html"><span class="kw719">fetestexcept</span></a><span class="br0">(</span><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw729">FE_DIVBYZERO</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">" FE_DIVBYZERO"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span><a href="c-numeric-fenv-fetestexcept.html"><span class="kw719">fetestexcept</span></a><span class="br0">(</span><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw730">FE_INEXACT</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">" FE_INEXACT"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span><a href="c-numeric-fenv-fetestexcept.html"><span class="kw719">fetestexcept</span></a><span class="br0">(</span><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw731">FE_INVALID</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">" FE_INVALID"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span><a href="c-numeric-fenv-fetestexcept.html"><span class="kw719">fetestexcept</span></a><span class="br0">(</span><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw732">FE_OVERFLOW</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">" FE_OVERFLOW"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span><a href="c-numeric-fenv-fetestexcept.html"><span class="kw719">fetestexcept</span></a><span class="br0">(</span><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw733">FE_UNDERFLOW</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">" FE_UNDERFLOW"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span><a href="c-numeric-fenv-fetestexcept.html"><span class="kw719">fetestexcept</span></a><span class="br0">(</span><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw728">FE_ALL_EXCEPT</span></a><span class="br0">)</span><span class="sy1">==</span><span class="nu0">0</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">" none"</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-numeric-fenv-feclearexcept.html"><span class="kw718">feclearexcept</span></a><span class="br0">(</span><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw728">FE_ALL_EXCEPT</span></a><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"<span class="es1">\n</span>"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw4">double</span> some_computation<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="coMULTI">/* 计算达到引发上溢的状态。 */</span>
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<span class="kw4">int</span> r <span class="sy1">=</span> feraiseexcept<span class="br0">(</span><a href="c-numeric-fenv-FE_exceptions.html"><span class="kw732">FE_OVERFLOW</span></a> <span class="sy3">|</span> <a href="c-numeric-fenv-FE_exceptions.html"><span class="kw730">FE_INEXACT</span></a><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"feraiseexcept() %s<span class="es1">\n</span>"</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="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> <span class="nu16">0.0</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
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<span class="br0">{</span>
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some_computation<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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show_fe_exceptions<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> <span class="nu0">0</span><span class="sy4">;</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">feraiseexcept() succeeds
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current exceptions raised: FE_INEXACT FE_OVERFLOW</pre></div>
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<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">引用</span></h3>
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<div class="t-ref-std-11">
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<ul>
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<li>C11 标准(ISO/IEC 9899:2011):</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.6.2.3 The feraiseexcept function (p: 210)</li>
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</ul>
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</dd>
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</dl>
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<div class="t-ref-std-c99">
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<ul>
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<li>C99 标准(ISO/IEC 9899:1999):</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.6.2.3 The feraiseexcept function (p: 191)</li>
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</ul>
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</dd>
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</dl>
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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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<td>
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<div class="t-dsc-member-div">
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<div><a href="c-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-c99">(C99)</span></span></span></div>
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</div>
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</td>
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<td>清除指定的浮点异常状态标志<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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<div class="t-dsc-member-div">
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<div><a href="c-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-c99">(C99)</span></span></span></div>
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</div>
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</td>
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<td>确认设置了哪些浮点异常状态标志<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>
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<div class="visualClear"></div>
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