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<div id="contentSub"><span class="subpages">&lt; <a href="c.html">c</a>&lrm; | <a href="c-numeric.html">numeric</a>&lrm; | <a href="c-numeric-fenv.html">fenv</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code>&lt;fenv.h&gt;</code></div>
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<div><span class="mw-geshi c source-c"><span class="kw4">int</span> feupdateenv<span class="br0">(</span> <span class="kw4">const</span> fenv_t<span class="sy2">*</span> envp <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-c99">(C99 &#36215;)</span></td>
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<p>&#39318;&#20808;&#65292;&#22238;&#24518;&#24403;&#21069;&#24341;&#21457;&#30340;&#28014;&#28857;&#24322;&#24120;&#65292;&#28982;&#21518;&#20174; <code>envp</code> &#25152;&#25351;&#21521;&#30340;&#23545;&#35937;&#24674;&#22797;&#28014;&#28857;&#29615;&#22659;&#65288;&#31867;&#20284; <span class="t-lc"><a href="c-numeric-fenv-feenv.html">fesetenv</a></span> &#65289;&#65292;&#20877;&#24341;&#21457;&#20445;&#23384;&#30340;&#28014;&#28857;&#24322;&#24120;&#12290;</p>
<p>&#27492;&#20989;&#25968;&#21487;&#29992;&#20110;&#32467;&#26463;&#20808;&#21069;&#35843;&#29992; <span class="t-lc"><a href="c-numeric-fenv-feholdexcept.html">feholdexcept</a></span> &#24314;&#31435;&#30340;&#19981;&#20572;&#27490;&#27169;&#24335;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>envp</td>
<td>-</td>
<td>&#25351;&#21521; <span class="t-c"><span class="mw-geshi c source-c">fenv_t</span></span> &#31867;&#22411;&#23545;&#35937;&#30340;&#25351;&#38024;&#65292;&#23545;&#35937;&#20026;&#20043;&#21069;&#21040; <span class="t-lc"><a href="c-numeric-fenv-feholdexcept.html">feholdexcept</a></span> &#25110; <code>fegetenv</code> &#30340;&#35843;&#29992;&#25152;&#35774;&#65292;&#25110;&#31561;&#20110; <span class="t-lc"><a href="c-numeric-fenv-FE_DFL_ENV.html">FE_DFL_ENV</a></span></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>&#25104;&#21151;&#26102;&#20026; <span class="t-c"><span class="mw-geshi c source-c">&#8203;<span class="nu0">0</span>&#8203;</span></span> &#65292;&#21542;&#21017;&#20026;&#38750;&#38646;&#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>
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<div class="c source-c">
<pre class="de1"><span class="co2">#include &lt;stdio.h&gt;</span>
<span class="co2">#include &lt;fenv.h&gt;</span>
<span class="co2">#include &lt;float.h&gt;</span>
<span class="co2">#pragma STDC FENV_ACCESS ON</span>
<span class="kw4">void</span> show_fe_exceptions<span class="br0">(</span><span class="kw4">void</span><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">&quot;current exceptions raised: &quot;</span><span class="br0">)</span><span class="sy4">;</span>
<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">&quot; FE_DIVBYZERO&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<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">&quot; FE_INEXACT&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<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">&quot; FE_INVALID&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<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">&quot; FE_OVERFLOW&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<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">&quot; FE_UNDERFLOW&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<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">&quot; none&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">&quot;<span class="es1">\n</span>&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw4">double</span> x2 <span class="br0">(</span><span class="kw4">double</span> x<span class="br0">)</span> <span class="coMULTI">/* &#20056;&#20108; */</span>
<span class="br0">{</span>
fenv_t curr_excepts<span class="sy4">;</span>
<span class="coMULTI">/* &#20445;&#23384;&#24182;&#28165;&#29702;&#24403;&#21069;&#28014;&#28857;&#29615;&#22659;&#12290; */</span>
<a href="c-numeric-fenv-feholdexcept.html"><span class="kw727">feholdexcept</span></a><span class="br0">(</span><span class="sy3">&amp;</span>curr_excepts<span class="br0">)</span><span class="sy4">;</span>
<span class="coMULTI">/* &#24341;&#21457;&#19981;&#20934;&#30830;&#21644;&#28322;&#20986;&#24322;&#24120;&#12290; */</span>
<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">&quot;In x2(): x = %f<span class="es1">\n</span>&quot;</span>, x<span class="sy1">=</span>x<span class="sy2">*</span><span class="nu16">2.0</span><span class="br0">)</span><span class="sy4">;</span>
show_fe_exceptions<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<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="kw730">FE_INEXACT</span></a><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* &#20174;&#35843;&#29992;&#26041;&#38544;&#34255;&#19981;&#20934;&#30830;&#24322;&#24120; */</span>
<span class="coMULTI">/* &#23558;&#35843;&#29992;&#26041;&#30340;&#24322;&#24120;&#65288;FE_INVALID&#65289;&#24182;&#20837; */</span>
<span class="coMULTI">/* &#21097;&#19979;&#30340;x2&#30340;&#24322;&#24120;&#65288;FE_OVERFLOW&#65289;&#12290; */</span>
feupdateenv<span class="br0">(</span><span class="sy3">&amp;</span>curr_excepts<span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">return</span> x<span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
<span class="br0">{</span>
<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>
<a href="c-numeric-fenv-feraiseexcept.html"><span class="kw720">feraiseexcept</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="sy4">;</span> <span class="coMULTI">/* &#19968;&#20123;&#24102;&#26377;&#38750;&#27861;&#21442;&#25968;&#30340;&#35745;&#31639; */</span>
show_fe_exceptions<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">&quot;x2(DBL_MAX) = %f<span class="es1">\n</span>&quot;</span>, x2<span class="br0">(</span><a href="c-types-limits.html"><span class="kw378">DBL_MAX</span></a><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
show_fe_exceptions<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">return</span> <span class="nu0">0</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
</div>
<p>&#36755;&#20986;&#65306;</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="text source-text">
<pre class="de1">current exceptions raised: FE_INVALID
In x2(): x = inf
current exceptions raised: FE_INEXACT FE_OVERFLOW
x2(DBL_MAX) = inf
current exceptions raised: FE_INVALID FE_OVERFLOW</pre></div>
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<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">&#24341;&#29992;</span></h3>
<div class="t-ref-std-11">
<ul>
<li>C11 &#26631;&#20934;&#65288;ISO/IEC 9899:2011&#65289;&#65306;</li>
</ul>
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<dd>
<ul>
<li>7.6.4.4 The feupdateenv function (p: 214-215)</li>
</ul>
</dd>
</dl>
<div class="t-ref-std-c99">
<ul>
<li>C99 &#26631;&#20934;&#65288;ISO/IEC 9899:1999&#65289;&#65306;</li>
</ul>
<dl>
<dd>
<ul>
<li>7.6.4.4 The feupdateenv function (p: 195-196)</li>
</ul>
</dd>
</dl>
</div>
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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<div class="t-dsc-member-div">
<div><a href="c-numeric-fenv-feholdexcept.html"><span class="t-lines"><span>feholdexcept</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div>
</div>
</td>
<td>&#20445;&#23384;&#24403;&#21069;&#29615;&#22659;&#30340;&#24322;&#24120;&#29366;&#24577;&#26631;&#24535;&#65292;&#20877;&#28165;&#38500;&#25152;&#26377;&#24322;&#24120;&#29366;&#24577;&#26631;&#24535;&#65292;&#24182;&#24573;&#30053;&#25152;&#26377;&#26410;&#26469;&#38169;&#35823;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="c-numeric-fenv-feenv.html"><span class="t-lines"><span>fegetenv</span><span>fesetenv</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div>
</div>
</td>
<td>&#20445;&#23384;&#25110;&#24674;&#22797;&#24403;&#21069;&#28014;&#28857;&#29615;&#22659;&#65292;&#21253;&#25324;&#24322;&#24120;&#30340;&#26631;&#24535;&#21644;&#25968;&#23383;&#30340;&#33293;&#24323;&#27169;&#24335;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="c-numeric-fenv-FE_DFL_ENV.html"><span class="t-lines"><span>FE_DFL_ENV</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div>
</div>
</td>
<td>&#40664;&#35748;&#28014;&#28857;&#29615;&#22659;<br />
<span class="t-mark">(&#23439;&#24120;&#37327;)</span></td>
</tr>
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