klarkxy/hustoj
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
master
hustoj/web/cppreference-zh/chmhelp/c-numeric-math-fabs.html
klarkxy 196e706fe4 上传cppreference
2025-08-01 12:57:54 +08:00

307 lines
16 KiB
HTML
Raw Permalink Blame History

<!DOCTYPE html>
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>fabs, fabsf, fabsl, fabsd32, fabsd64, fabsd128</title>
<link rel="stylesheet" href="ext.css" />
<link rel="stylesheet" href="site_modules.css" />
</head>
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_numeric_math_fabs skin-cppreference2 action-view cpp-navbar">
<div id="cpp-content-base">
<div id="content"><a id="top"></a>
<h1 id="firstHeading" class="firstHeading">fabs, fabsf, fabsl, fabsd32, fabsd64, fabsd128</h1>
<div id="bodyContent">
<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-math.html">math</a></span></div>
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
<table class="t-dcl-begin">
<tbody>
<tr class="t-dsc-header">
<td>
<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code>&lt;math.h&gt;</code></div>
</td>
<td></td>
<td></td>
</tr>
<tr class="t-dcl t-since-c99">
<td>
<div><span class="mw-geshi c source-c"><span class="kw4">float</span> &nbsp; &nbsp; &nbsp; fabsf<span class="br0">(</span> <span class="kw4">float</span> arg <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>
</tr>
<tr class="t-dcl">
<td>
<div><span class="mw-geshi c source-c"><span class="kw4">double</span> &nbsp; &nbsp; &nbsp;fabs<span class="br0">(</span> <span class="kw4">double</span> arg <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(2)</td>
<td class="t-dcl-nopad"></td>
</tr>
<tr class="t-dcl t-since-c99">
<td>
<div><span class="mw-geshi c source-c"><span class="kw4">long</span> <span class="kw4">double</span> fabsl<span class="br0">(</span> <span class="kw4">long</span> <span class="kw4">double</span> arg <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(3)</td>
<td><span class="t-mark-rev t-since-c99">(C99 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-c23">
<td>
<div><span class="mw-geshi c source-c">_Decimal32 &nbsp;fabsd32<span class="br0">(</span> _Decimal32 arg <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(4)</td>
<td><span class="t-mark-rev t-since-c23">(C23 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-c23">
<td>
<div><span class="mw-geshi c source-c">_Decimal64 &nbsp;fabsd64<span class="br0">(</span> _Decimal64 arg <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(5)</td>
<td><span class="t-mark-rev t-since-c23">(C23 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-c23">
<td>
<div><span class="mw-geshi c source-c">_Decimal128 fabsd128<span class="br0">(</span> _Decimal128 arg <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(6)</td>
<td><span class="t-mark-rev t-since-c23">(C23 &#36215;)</span></td>
</tr>
<tr class="t-dsc-header">
<td>
<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code>&lt;tgmath.h&gt;</code></div>
</td>
<td></td>
<td></td>
</tr>
<tr class="t-dcl t-since-c99">
<td>
<div><span class="mw-geshi c source-c"><span class="co2">#define fabs( arith )</span></span></div>
</td>
<td>(7)</td>
<td><span class="t-mark-rev t-since-c99">(C99 &#36215;)</span></td>
</tr>
<tr class="t-dcl-sep">
<td></td>
<td></td>
<td></td>
</tr>
</tbody>
</table>
<div class="t-li1"><span class="t-li">1-6)</span> &#35745;&#31639;&#28014;&#28857;&#20540; <code>arg</code> &#30340;&#32477;&#23545;&#20540;&#12290;
<table class="t-rev-begin">
<tr class="t-rev t-since-c23">
<td>
<p>&#25317;&#26377;&#21313;&#36827;&#21046;&#28014;&#28857;&#21442;&#25968;&#30340;&#20989;&#25968;&#24403;&#19988;&#20165;&#24403;&#23454;&#29616;&#39044;&#23450;&#20041; <code>__STDC_IEC_60559_DFP__</code> &#65288;&#21363;&#23454;&#29616;&#25903;&#25345;&#21313;&#36827;&#21046;&#28014;&#28857;&#25968;&#65289;&#25165;&#34987;&#22768;&#26126;&#12290;</p>
</td>
<td><span class="t-mark-rev t-since-c23">(C23 &#36215;)</span></td>
</tr>
</table>
</div>
<div class="t-li1"><span class="t-li">7)</span> &#27867;&#22411;&#23439;&#65306;&#33509;&#23454;&#21442;&#25317;&#26377; <span class="t-rev-inl t-since-c23"><span><span class="t-c"><span class="mw-geshi c source-c">_Decimal128</span></span>&#12289; <span class="t-c"><span class="mw-geshi c source-c">_Decimal64</span></span>&#12289; <span class="t-c"><span class="mw-geshi c source-c">_Decimal32</span></span>&#12289;</span> <span><span class="t-mark-rev t-since-c23">(C23 &#36215;)</span></span></span><span class="t-c"><span class="mw-geshi c source-c"><span class="kw4">long</span> <span class="kw4">double</span></span></span>&#12289; <span class="t-c"><span class="mw-geshi c source-c"><span class="kw4">double</span></span></span> &#25110; <span class="t-c"><span class="mw-geshi c source-c"><span class="kw4">float</span></span></span> &#31867;&#22411;&#65292;&#21017;&#20998;&#21035;&#35843;&#29992; <span class="t-rev-inl t-since-c23"><span><code>fabsd128</code>&#12289; <code>fabsd64</code>&#12289; <code>fabsd32</code>&#12289;</span> <span><span class="t-mark-rev t-since-c23">(C23 &#36215;)</span></span></span><code>fabsl</code>&#12289; <code>fabs</code> &#25110; <code>fabsf</code> &#12290;&#21542;&#21017;&#33509;&#23454;&#21442;&#25317;&#26377;&#25972;&#25968;&#31867;&#22411;&#65292;&#21017;&#35843;&#29992; <code>fabs</code> &#12290;&#21542;&#21017;&#33509;&#23454;&#21442;&#20026;&#22797;&#25968;&#65292;&#21017;&#23439;&#35843;&#29992;&#23545;&#24212;&#30340;&#22797;&#20989;&#25968;&#65288; <span class="t-lc"><a href="c-numeric-complex-cabs.html">cabsf</a></span>&#12289; <span class="t-lc"><a href="c-numeric-complex-cabs.html">cabs</a></span>&#12289; <span class="t-lc"><a href="c-numeric-complex-cabs.html">cabsl</a></span> &#65289;&#12290;&#21542;&#21017;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</div>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<table class="t-par-begin">
<tr class="t-par">
<td>arg</td>
<td>-</td>
<td>&#28014;&#28857;&#20540;</td>
</tr>
<tr class="t-par">
<td>arith</td>
<td>-</td>
<td>&#28014;&#28857;&#25110;&#25972;&#25968;&#20540;</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#33509;&#25104;&#21151;&#65292;&#21017;&#36820;&#22238; <code>arg</code> &#30340;&#32477;&#23545;&#20540;&#65288; <span class="mjax" style="display:none">\(\small |arg| \)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">|arg|</span> &#65289;&#12290;&#20540;&#26159;&#20934;&#30830;&#30340;&#65292;&#19988;&#19981;&#20381;&#36182;&#20219;&#20309;&#33293;&#20837;&#27169;&#24335;&#12290;</p>
<h3><span class="mw-headline" id=".E9.94.99.E8.AF.AF.E5.A4.84.E7.90.86">&#38169;&#35823;&#22788;&#29702;</span></h3>
<p>&#27492;&#20989;&#25968;&#19981;&#21463;&#21046;&#20110;&#20219;&#20309;&#25351;&#23450;&#20110; <a href="c-numeric-math-math_errhandling.html"><tt>math_errhandling</tt></a> &#30340;&#38169;&#35823;&#26465;&#20214;&#12290;</p>
<p>&#33509;&#23454;&#29616;&#25903;&#25345; IEEE &#28014;&#28857;&#31639;&#26415;&#65288; IEC 60559 &#65289;&#65292;&#21017;</p>
<ul>
<li>&#33509;&#21442;&#25968;&#20026; &plusmn;0 &#65292;&#21017;&#36820;&#22238; +0</li>
<li>&#33509;&#21442;&#25968;&#20026; &plusmn;&infin; &#65292;&#21017;&#36820;&#22238; +&infin;</li>
<li>&#33509;&#21442;&#25968;&#20026; NaN &#65292;&#21017;&#36820;&#22238; NaN</li>
</ul>
<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="coMULTI">/* &#27492;&#25968;&#20540;&#31215;&#20998;&#20551;&#23450;&#25152;&#26377;&#38754;&#31215;&#22343;&#20026;&#27491;&#12290; */</span>
<span class="co2">#define PI 3.14159</span>
<span class="kw4">double</span> num_int <span class="br0">(</span><span class="kw4">double</span> a, <span class="kw4">double</span> b,
<span class="kw4">double</span> f<span class="br0">(</span><span class="kw4">double</span><span class="br0">)</span>,
<span class="kw4">unsigned</span> n<span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">if</span> <span class="br0">(</span>a <span class="sy1">==</span> b<span class="br0">)</span> <span class="kw1">return</span> <span class="nu16">0.0</span><span class="sy4">;</span>
<span class="kw1">if</span> <span class="br0">(</span>n <span class="sy1">==</span> <span class="nu0">0</span><span class="br0">)</span> n<span class="sy1">=</span><span class="nu0">1</span><span class="sy4">;</span> <span class="coMULTI">/* &#36991;&#20813;&#38500;&#20197;&#38646; */</span>
<span class="kw4">double</span> h <span class="sy1">=</span> <span class="br0">(</span>b<span class="sy2">-</span>a<span class="br0">)</span><span class="sy2">/</span>n<span class="sy4">;</span>
<span class="kw4">double</span> sum <span class="sy1">=</span> <span class="nu16">0.0</span><span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">unsigned</span> k<span class="sy1">=</span><span class="nu0">0</span><span class="sy4">;</span> k <span class="sy1">&lt;</span> n<span class="sy4">;</span> <span class="sy2">++</span>k<span class="br0">)</span>
sum <span class="sy2">+</span><span class="sy1">=</span> h<span class="sy2">*</span>fabs<span class="br0">(</span>f<span class="br0">(</span>a<span class="sy2">+</span>k<span class="sy2">*</span>h<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">return</span> sum<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-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">&quot;fabs(+3) = %f<span class="es1">\n</span>&quot;</span>, fabs<span class="br0">(</span><span class="sy2">+</span><span class="nu16">3.0</span><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;fabs(-3) = %f<span class="es1">\n</span>&quot;</span>, fabs<span class="br0">(</span><span class="sy2">-</span><span class="nu16">3.0</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="co1">// &#29305;&#27530;&#20540;</span>
<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">&quot;fabs(-0) = %f<span class="es1">\n</span>&quot;</span>, fabs<span class="br0">(</span><span class="sy2">-</span><span class="nu16">0.0</span><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;fabs(-Inf) = %f<span class="es1">\n</span>&quot;</span>, fabs<span class="br0">(</span><span class="sy2">-</span>INFINITY<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;%f<span class="es1">\n</span>&quot;</span>, num_int<span class="br0">(</span><span class="nu16">0.0</span>,<span class="nu0">2</span><span class="sy2">*</span>PI,<a href="c-numeric-math-sin.html"><span class="kw668">sin</span></a>,<span class="nu0">100000</span><span class="br0">)</span><span class="br0">)</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">fabs(+3) = 3.000000
fabs(-3) = 3.000000
fabs(-0) = 0.000000
fabs(-Inf) = inf
4.000000</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-17">
<ul>
<li>C17 &#26631;&#20934;&#65288;ISO/IEC 9899:2018&#65289;&#65306;</li>
</ul>
<dl>
<dd>
<ul>
<li>7.12.7.2 The fabs functions (p: 181)</li>
</ul>
</dd>
</dl>
<dl>
<dd>
<ul>
<li>7.25 Type-generic math &lt;tgmath.h&gt; (p: 272-273)</li>
</ul>
</dd>
</dl>
<dl>
<dd>
<ul>
<li>F.10.4.2 The fabs functions (p: 382)</li>
</ul>
</dd>
</dl>
</div>
<div class="t-ref-std-11">
<ul>
<li>C11 &#26631;&#20934;&#65288;ISO/IEC 9899:2011&#65289;&#65306;</li>
</ul>
<dl>
<dd>
<ul>
<li>7.12.7.2 The fabs functions (p: 248)</li>
</ul>
</dd>
</dl>
<dl>
<dd>
<ul>
<li>7.25 Type-generic math &lt;tgmath.h&gt; (p: 373-375)</li>
</ul>
</dd>
</dl>
<dl>
<dd>
<ul>
<li>F.10.4.2 The fabs functions (p: 524)</li>
</ul>
</dd>
</dl>
</div>
<div class="t-ref-std-c99">
<ul>
<li>C99 &#26631;&#20934;&#65288;ISO/IEC 9899:1999&#65289;&#65306;</li>
</ul>
<dl>
<dd>
<ul>
<li>7.12.7.2 The fabs functions (p: 228-229)</li>
</ul>
</dd>
</dl>
<dl>
<dd>
<ul>
<li>7.22 Type-generic math &lt;tgmath.h&gt; (p: 335-337)</li>
</ul>
</dd>
</dl>
<dl>
<dd>
<ul>
<li>F.9.4.2 The fabs functions (p: 460)</li>
</ul>
</dd>
</dl>
</div>
<div class="t-ref-std-c89">
<ul>
<li>C89/C90 &#26631;&#20934;&#65288;ISO/IEC 9899:1990&#65289;&#65306;</li>
</ul>
<dl>
<dd>
<ul>
<li>4.5.6.2 The fabs function</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-math-abs.html"><span class="t-lines"><span>abs</span><span>labs</span><span>llabs</span></span></a></div>
<div><span class="t-lines"><span></span><span></span><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div>
</div>
</td>
<td>&#35745;&#31639;&#25972;&#25968;&#20540;&#30340;&#32477;&#23545;&#20540;&#65288; <span class="mjax" style="display:none">\(\small{|x|}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">|x|</span> &#65289;<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-math-copysign.html"><span class="t-lines"><span>copysign</span><span>copysignf</span><span>copysignl</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>
</div>
</td>
<td>&#20174;&#19968;&#20010;&#32473;&#23450;&#20540;&#30340;&#32477;&#23545;&#20540;&#21644;&#21478;&#19968;&#20010;&#32473;&#23450;&#20540;&#30340;&#31526;&#21495;&#20135;&#29983;&#20540;<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-math-signbit.html"><span class="t-lines"><span>signbit</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>&#26816;&#26597;&#32473;&#23450;&#25968;&#26159;&#19981;&#26159;&#36127;&#25968;<br />
<span class="t-mark">(&#23439;&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="c-numeric-complex-cabs.html"><span class="t-lines"><span>cabs</span><span>cabsf</span><span>cabsl</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>
</div>
</td>
<td>&#35745;&#31639;&#22797;&#25968;&#30340;&#27169;&#65288;&#32477;&#23545;&#20540;&#65289;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
</table>
</div>
<div class="visualClear"></div>
</div>
</div>
</div>
</body>
</html>
Reference in New Issue View Git Blame Copy Permalink