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<title>fegetround, fesetround</title>
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<h1 id="firstHeading" class="firstHeading">fegetround, fesetround</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> fesetround<span class="br0">(</span> <span class="kw4">int</span> <a href="c-numeric-math-round.html"><span class="kw689">round</span></a> <span class="br0">)</span><span class="sy4">;</span></span></div>
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<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> fegetround<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-c99">(C99 &#36215;)</span></td>
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<div class="t-li1"><span class="t-li">1)</span> &#35797;&#22270;&#24314;&#31435;&#31561;&#20110;&#21442;&#25968; <code>round</code> &#30340;&#28014;&#28857;&#33293;&#20837;&#26041;&#21521;&#65292;&#26399;&#24453;&#21442;&#25968;&#20026;<a href="c-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#20043;&#19968;&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#36820;&#22238;&#23545;&#24212;&#24403;&#21069;&#33293;&#20837;&#26041;&#21521;&#30340;<a href="c-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#12290;</div>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>round</td>
<td>-</td>
<td>&#33293;&#20837;&#26041;&#21521;&#65292;<a href="c-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#20043;&#19968;</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>1) &#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>
<p>2) &#25551;&#36848;&#24403;&#21069;&#33293;&#20837;&#26041;&#21521;&#30340;<a href="c-numeric-fenv-FE_round.html">&#28014;&#28857;&#33293;&#20837;&#23439;</a>&#65292;&#25110;&#33509;&#19981;&#33021;&#30830;&#23450;&#26041;&#21521;&#21017;&#20026;&#36127;&#20540;</p>
<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">&#27880;&#24847;</span></h3>
<p>&#24403;&#21069;&#33293;&#20837;&#26041;&#21521;&#21453;&#26144;&#26368;&#36817;&#30340; <code>fesetround</code> &#30340;&#25928;&#26524;&#65292;&#20134;&#33021;&#20197; <span class="t-lc"><a href="c-types-limits-FLT_ROUNDS.html">FLT_ROUNDS</a></span> &#26597;&#35810;&#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;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_current_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>fegetround<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">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="coMULTI">/* &#40664;&#35748;&#33293;&#20837;&#26041;&#27861; */</span>
show_fe_current_rounding_method<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;+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>
<span class="coMULTI">/* &#20445;&#23384;&#33293;&#20837;&#26041;&#27861;&#12290; */</span>
<span class="kw4">int</span> curr_method <span class="sy1">=</span> fegetround<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="coMULTI">/* &#20020;&#26102;&#26356;&#25913;&#24403;&#21069;&#33293;&#20837;&#26041;&#27861;&#12290; */</span>
fesetround<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>
show_fe_current_rounding_method<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;+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>
<span class="coMULTI">/* &#24674;&#22797;&#33293;&#20837;&#26041;&#27861;&#12290; */</span>
fesetround<span class="br0">(</span>curr_method<span class="br0">)</span><span class="sy4">;</span>
show_fe_current_rounding_method<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>
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<p>&#21487;&#33021;&#30340;&#36755;&#20986;&#65306;</p>
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<pre class="de1">current rounding method: FE_TONEAREST
+11.5 -&gt; +12.0
+12.5 -&gt; +12.0
current rounding method: FE_DOWNWARD
+11.5 -&gt; +11.0
+12.5 -&gt; +12.0
current rounding method: FE_TONEAREST</pre></div>
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<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">&#24341;&#29992;</span></h3>
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<li>C11 &#26631;&#20934;&#65288;ISO/IEC 9899:2011&#65289;&#65306;</li>
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<li>7.6.3.1 The fegetround function (p: 212)</li>
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<li>7.6.3.2 The fesetround function (p: 212-213)</li>
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<div class="t-ref-std-c99">
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<li>C99 &#26631;&#20934;&#65288;ISO/IEC 9899:1999&#65289;&#65306;</li>
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<li>7.6.3.1 The fegetround function (p: 193)</li>
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<li>7.6.3.2 The fesetround function (p: 193-194)</li>
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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="c-numeric-math-nearbyint.html"><span class="t-lines"><span>nearbyint</span><span>nearbyintf</span><span>nearbyintl</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><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div>
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<td>&#29992;&#24403;&#21069;&#33293;&#20837;&#27169;&#24335;&#21462;&#25972;&#21040;&#25972;&#25968;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<div><a href="c-numeric-math-rint.html"><span class="t-lines"><span>rint</span><span>rintf</span><span>rintl</span><span>lrint</span><span>lrintf</span><span>lrintl</span><span>llrint</span><span>llrintf</span><span>llrintl</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><span class="t-mark-rev t-since-c99">(C99)</span></span><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><span class="t-mark-rev t-since-c99">(C99)</span></span><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><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div>
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<td>&#20351;&#29992;&#24403;&#21069;&#33293;&#20837;&#27169;&#24335;&#21462;&#25972;&#21040;&#25972;&#25968;&#65292;&#33509;&#32467;&#26524;&#26377;&#35823;&#21017;&#20135;&#29983;&#24322;&#24120;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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