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<h1 id="firstHeading" class="firstHeading">fegetenv, fesetenv</h1>
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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> fegetenv<span class="br0">(</span> fenv_t<span class="sy2">*</span> envp <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(1)</td>
<td><span class="t-mark-rev t-since-c99">(C99 &#36215;)</span></td>
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<div><span class="mw-geshi c source-c"><span class="kw4">int</span> fesetenv<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>
</td>
<td>(2)</td>
<td><span class="t-mark-rev t-since-c99">(C99 &#36215;)</span></td>
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<p>1) &#35797;&#22270;&#23384;&#20648;&#28014;&#28857;&#29615;&#22659;&#30340;&#29366;&#24577;&#20110; <code>envp</code> &#25152;&#25351;&#21521;&#30340;&#23545;&#35937;&#12290;</p>
<p>2) &#35797;&#22270;&#20174; <code>envp</code> &#25152;&#25351;&#21521;&#30340;&#23545;&#35937;&#24314;&#31435;&#28014;&#28857;&#29615;&#22659;&#29366;&#24577;&#12290;&#23545;&#35937;&#30340;&#20540;&#24517;&#39035;&#26159;&#20197;&#20808;&#21069;&#35843;&#29992; <span class="t-lc"><a href="c-numeric-fenv-feholdexcept.html">feholdexcept</a></span> &#25110; <code>fegetenv</code> &#33719;&#24471;&#20540;&#25110;&#26159;&#28014;&#28857;&#23439;&#24120;&#37327;&#12290;&#33509; <code>envp</code> &#20013;&#35774;&#32622;&#20102;&#20219;&#20309;&#28014;&#28857;&#29366;&#24577;&#26631;&#24535;&#65292;&#21017;&#29615;&#22659;&#20013;&#26631;&#24535;&#21464;&#20026;&#34987;&#35774;&#32622;&#65288;&#28982;&#21518;&#21487;&#29992; <span class="t-lc"><a href="c-numeric-fenv-fetestexcept.html">fetestexcept</a></span> &#27979;&#35797;&#65289;&#65292;&#20294;&#19981;&#24341;&#21457;&#23545;&#24212;&#30340;&#28014;&#28857;&#24322;&#24120;&#65288;&#25191;&#34892;&#25345;&#32493;&#32780;&#19981;&#20013;&#26029;&#65289;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<table class="t-par-begin">
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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;&#35813;&#23545;&#35937;&#20445;&#26377;&#28014;&#28857;&#29615;&#22659;&#30340;&#29366;&#24577;</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#25104;&#21151;&#26102;&#36820;&#22238; <span class="t-c"><span class="mw-geshi c source-c">&#8203;<span class="nu0">0</span>&#8203;</span></span> &#65292;&#21542;&#21017;&#36820;&#22238;&#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>
<div dir="ltr" class="mw-geshi" style="text-align: left;">
<div class="c source-c">
<pre class="de1"><span class="co2">#include &lt;stdio.h&gt;</span>
<span class="co2">#include &lt;math.h&gt;</span>
<span class="co2">#include &lt;fenv.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="kw849">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="kw728">FE_DIVBYZERO</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw849">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="kw729">FE_INEXACT</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw849">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="kw730">FE_INVALID</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw849">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="kw731">FE_OVERFLOW</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw849">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="kw732">FE_UNDERFLOW</span></a><span class="br0">)</span><span class="br0">)</span> <a href="c-io-fprintf.html"><span class="kw849">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="kw727">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="kw849">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="kw849">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">void</span> show_fe_rounding_method<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="kw849">printf</span></a><span class="br0">(</span><span class="st0">&quot;current rounding method: &quot;</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">switch</span> <span class="br0">(</span><a href="c-numeric-fenv-feround.html"><span class="kw723">fegetround</span></a><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">case</span> <a href="c-numeric-fenv-FE_round.html"><span class="kw734">FE_TONEAREST</span></a><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw849">printf</span></a> <span class="br0">(</span><span class="st0">&quot;FE_TONEAREST&quot;</span><span class="br0">)</span><span class="sy4">;</span> <span class="kw1">break</span><span class="sy4">;</span>
<span class="kw1">case</span> <a href="c-numeric-fenv-FE_round.html"><span class="kw733">FE_DOWNWARD</span></a><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw849">printf</span></a> <span class="br0">(</span><span class="st0">&quot;FE_DOWNWARD&quot;</span><span class="br0">)</span><span class="sy4">;</span> <span class="kw1">break</span><span class="sy4">;</span>
<span class="kw1">case</span> <a href="c-numeric-fenv-FE_round.html"><span class="kw736">FE_UPWARD</span></a><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw849">printf</span></a> <span class="br0">(</span><span class="st0">&quot;FE_UPWARD&quot;</span><span class="br0">)</span><span class="sy4">;</span> <span class="kw1">break</span><span class="sy4">;</span>
<span class="kw1">case</span> <a href="c-numeric-fenv-FE_round.html"><span class="kw735">FE_TOWARDZERO</span></a><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw849">printf</span></a> <span class="br0">(</span><span class="st0">&quot;FE_TOWARDZERO&quot;</span><span class="br0">)</span><span class="sy4">;</span> <span class="kw1">break</span><span class="sy4">;</span>
<span class="kw1">default</span><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw849">printf</span></a> <span class="br0">(</span><span class="st0">&quot;unknown&quot;</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw849">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">void</span> show_fe_environment<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
<span class="br0">{</span>
show_fe_exceptions<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
show_fe_rounding_method<span class="br0">(</span><span class="br0">)</span><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>
fenv_t curr_env<span class="sy4">;</span>
<span class="kw4">int</span> rtn<span class="sy4">;</span>
<span class="coMULTI">/* &#26174;&#31034;&#40664;&#35748;&#29615;&#22659;&#12290; */</span>
show_fe_environment<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw849">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="coMULTI">/* &#22312;&#40664;&#35748;&#29615;&#22659;&#19979;&#20570;&#19968;&#20123;&#35745;&#31639;&#12290; */</span>
<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">&quot;+11.5 -&gt; %+4.1f<span class="es1">\n</span>&quot;</span>, <a href="c-numeric-math-rint.html"><span class="kw693">rint</span></a><span class="br0">(</span><span class="sy2">+</span><span class="nu16">11.5</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* &#20004;&#25972;&#25968;&#30340;&#20013;&#22830;&#20540; */</span>
<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">&quot;+12.5 -&gt; %+4.1f<span class="es1">\n</span>&quot;</span>, <a href="c-numeric-math-rint.html"><span class="kw693">rint</span></a><span class="br0">(</span><span class="sy2">+</span><span class="nu16">12.5</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* &#20004;&#25972;&#25968;&#30340;&#20013;&#22830;&#20540; */</span>
show_fe_environment<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw849">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="coMULTI">/* &#20445;&#23384;&#24403;&#21069;&#29615;&#22659;&#12290; */</span>
rtn <span class="sy1">=</span> fegetenv<span class="br0">(</span><span class="sy3">&amp;</span>curr_env<span class="br0">)</span><span class="sy4">;</span>
<span class="coMULTI">/* &#20197;&#26032;&#33293;&#20837;&#26041;&#27861;&#36827;&#34892;&#19968;&#20123;&#35745;&#31639;&#12290; */</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="kw727">FE_ALL_EXCEPT</span></a><span class="br0">)</span><span class="sy4">;</span>
<a href="c-numeric-fenv-feround.html"><span class="kw724">fesetround</span></a><span class="br0">(</span><a href="c-numeric-fenv-FE_round.html"><span class="kw733">FE_DOWNWARD</span></a><span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">&quot;1.0/0.0 = %f<span class="es1">\n</span>&quot;</span>, <span class="nu16">1.0</span><span class="sy2">/</span><span class="nu16">0.0</span><span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">&quot;+11.5 -&gt; %+4.1f<span class="es1">\n</span>&quot;</span>, <a href="c-numeric-math-rint.html"><span class="kw693">rint</span></a><span class="br0">(</span><span class="sy2">+</span><span class="nu16">11.5</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">&quot;+12.5 -&gt; %+4.1f<span class="es1">\n</span>&quot;</span>, <a href="c-numeric-math-rint.html"><span class="kw693">rint</span></a><span class="br0">(</span><span class="sy2">+</span><span class="nu16">12.5</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
show_fe_environment<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<a href="c-io-fprintf.html"><span class="kw849">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="coMULTI">/* &#24674;&#22797;&#20808;&#21069;&#29615;&#22659;&#12290; */</span>
rtn <span class="sy1">=</span> fesetenv<span class="br0">(</span><span class="sy3">&amp;</span>curr_env<span class="br0">)</span><span class="sy4">;</span>
show_fe_environment<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: none
current rounding method: FE_TONEAREST
+11.5 -&gt; +12.0
+12.5 -&gt; +12.0
current exceptions raised: FE_INEXACT
current rounding method: FE_TONEAREST
1.0/0.0 = inf
+11.5 -&gt; +11.0
+12.5 -&gt; +12.0
current exceptions raised: FE_DIVBYZERO FE_INEXACT
current rounding method: FE_DOWNWARD
current exceptions raised: FE_INEXACT
current rounding method: FE_TONEAREST</pre></div>
</div>
</div>
<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>
<dl>
<dd>
<ul>
<li>7.6.4.1 The fegetenv function (p: 213)</li>
</ul>
</dd>
</dl>
<dl>
<dd>
<ul>
<li>7.6.4.3 The fesetenv function (p: 214)</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>7.6.4.1 The fegetenv function (p: 194)</li>
</ul>
</dd>
</dl>
<dl>
<dd>
<ul>
<li>7.6.4.3 The fesetenv function (p: 195)</li>
</ul>
</dd>
</dl>
</div>
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
<table class="t-dsc-begin">
<tr class="t-dsc">
<td>
<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-feupdateenv.html"><span class="t-lines"><span>feupdateenv</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>&#24674;&#22797;&#20043;&#21069;&#20445;&#23384;&#30340;&#28014;&#28857;&#29615;&#22659;&#65292;&#24182;&#24341;&#21457;&#20043;&#21069;&#24050;&#32463;&#24341;&#21457;&#36807;&#30340;&#24322;&#24120;&#65292;&#20351;&#20854;&#23384;&#22312;&#20110;&#24403;&#21069;&#20869;&#23384;&#29615;&#22659;&#20013;<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>
</table>
</div>
</div>
<div class="visualClear"></div>
</div>
</div>
</div>
</body>
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