klarkxy/hustoj
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
c22c788cfad2800379086be15afefc19f12044c6
hustoj/web/cppreference-zh/chmhelp/cpp-numeric-math-fpclassify.html
klarkxy 196e706fe4 上传cppreference
2025-08-01 12:57:54 +08:00

169 lines
11 KiB
HTML
Raw 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>std::fpclassify</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-cpp_numeric_math_fpclassify skin-cppreference2 action-view cpp-navbar">
<div id="cpp-content-base">
<div id="content"><a id="top"></a>
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>fpclassify</h1>
<div id="bodyContent">
<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-numeric.html">numeric</a>&lrm; | <a href="cpp-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><a href="cpp-header-cmath.html">&lt;cmath&gt;</a></code></div>
</td>
<td></td>
<td></td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td>
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fpclassify<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-cxx11">(C++11 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td>
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fpclassify<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><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td>
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fpclassify<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-cxx11">(C++11 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td>
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fpclassify<span class="br0">(</span> IntegralType arg <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(4)</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#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">1-3)</span> &#24402;&#31867;&#28014;&#28857;&#20540; <code>arg</code> &#21040;&#19979;&#21015;&#31867;&#21035;&#20013;&#65306;&#38646;&#12289;&#38750;&#27491;&#35268;&#12289;&#27491;&#35268;&#12289;&#26080;&#31351;&#22823;&#12289; NaN &#25110;&#23454;&#29616;&#23450;&#20041;&#31867;&#21035;&#12290;</div>
<div class="t-li1"><span class="t-li">4)</span> &#25509;&#21463;&#20219;&#20309;<a href="cpp-types-is_integral.html">&#25972;&#25968;&#31867;&#22411;</a> <code>from</code> &#21442;&#25968;&#30340;&#37325;&#36733;&#38598;&#25110;&#20989;&#25968;&#27169;&#26495;&#12290;&#31561;&#20215;&#20110; <span class="t-v">(2)</span> &#65288;&#23558;&#21442;&#25968;&#36716;&#22411;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">double</span></span></span> &#65289;&#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>
</table>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#25351;&#26126; <code>arg</code> &#31867;&#21035;&#30340; <span class="t-lc"><a href="cpp-numeric-math-FP_categories.html">FP_INFINITE</a></span> &#12289; <span class="t-lc"><a href="cpp-numeric-math-FP_categories.html">FP_NAN</a></span> &#12289; <span class="t-lc"><a href="cpp-numeric-math-FP_categories.html">FP_NORMAL</a></span> &#12289; <span class="t-lc"><a href="cpp-numeric-math-FP_categories.html">FP_SUBNORMAL</a></span> &#12289; <span class="t-lc"><a href="cpp-numeric-math-FP_categories.html">FP_ZERO</a></span> &#25110;&#23454;&#29616;&#23450;&#20041;&#31867;&#22411;&#20043;&#19968;&#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="cpp source-cpp">
<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;cmath&gt;</span>
<span class="co2">#include &lt;cfloat&gt;</span>
<span class="kw4">const</span> <span class="kw4">char</span><span class="sy2">*</span> show_classification<span class="br0">(</span><span class="kw4">double</span> x<span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">switch</span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">fpclassify</span><span class="br0">(</span>x<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">case</span> <a href="cpp-numeric-math-FP_categories.html"><span class="kw1381">FP_INFINITE</span></a><span class="sy4">:</span> <span class="kw1">return</span> <span class="st0">&quot;Inf&quot;</span><span class="sy4">;</span>
<span class="kw1">case</span> <a href="cpp-numeric-math-FP_categories.html"><span class="kw1382">FP_NAN</span></a><span class="sy4">:</span> <span class="kw1">return</span> <span class="st0">&quot;NaN&quot;</span><span class="sy4">;</span>
<span class="kw1">case</span> <a href="cpp-numeric-math-FP_categories.html"><span class="kw1383">FP_NORMAL</span></a><span class="sy4">:</span> <span class="kw1">return</span> <span class="st0">&quot;normal&quot;</span><span class="sy4">;</span>
<span class="kw1">case</span> <a href="cpp-numeric-math-FP_categories.html"><span class="kw1384">FP_SUBNORMAL</span></a><span class="sy4">:</span> <span class="kw1">return</span> <span class="st0">&quot;subnormal&quot;</span><span class="sy4">;</span>
<span class="kw1">case</span> <a href="cpp-numeric-math-FP_categories.html"><span class="kw1385">FP_ZERO</span></a><span class="sy4">:</span> <span class="kw1">return</span> <span class="st0">&quot;zero&quot;</span><span class="sy4">;</span>
<span class="kw1">default</span><span class="sy4">:</span> <span class="kw1">return</span> <span class="st0">&quot;unknown&quot;</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="br0">}</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;1.0/0.0 is &quot;</span> <span class="sy1">&lt;&lt;</span> show_classification<span class="br0">(</span><span class="nu0">1</span><span class="sy2">/</span><span class="nu16">0.0</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;0.0/0.0 is &quot;</span> <span class="sy1">&lt;&lt;</span> show_classification<span class="br0">(</span><span class="nu16">0.0</span><span class="sy2">/</span><span class="nu16">0.0</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;DBL_MIN/2 is &quot;</span> <span class="sy1">&lt;&lt;</span> show_classification<span class="br0">(</span><a href="cpp-types-climits.html"><span class="kw412">DBL_MIN</span></a><span class="sy2">/</span><span class="nu0">2</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;-0.0 is &quot;</span> <span class="sy1">&lt;&lt;</span> show_classification<span class="br0">(</span><span class="sy2">-</span><span class="nu16">0.0</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;1.0 is &quot;</span> <span class="sy1">&lt;&lt;</span> show_classification<span class="br0">(</span><span class="nu16">1.0</span><span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</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">1.0/0.0 is Inf
0.0/0.0 is NaN
DBL_MIN/2 is subnormal
-0.0 is zero
1.0 is normal</pre></div>
</div>
</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="cpp-numeric-math-isfinite.html"><span class="t-lines"><span>isfinite</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
</div>
</td>
<td>&#26816;&#26597;&#32473;&#23450;&#25968;&#26159;&#21542;&#25317;&#26377;&#26377;&#38480;&#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="cpp-numeric-math-isinf.html"><span class="t-lines"><span>isinf</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
</div>
</td>
<td>&#26816;&#26597;&#32473;&#23450;&#25968;&#26159;&#21542;&#20026;&#26080;&#38480;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-numeric-math-isnan.html"><span class="t-lines"><span>isnan</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
</div>
</td>
<td>&#26816;&#26597;&#32473;&#23450;&#30340;&#25968;&#26159;&#21542; NaN<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-numeric-math-isnormal.html"><span class="t-lines"><span>isnormal</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
</div>
</td>
<td>&#26816;&#26597;&#32473;&#23450;&#25968;&#26159;&#21542;&#27491;&#35268;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-types-numeric_limits.html"><span class="t-lines"><span>numeric_limits</span></span></a></div>
</div>
</td>
<td>&#25552;&#20379;&#26597;&#35810;&#25152;&#26377;&#22522;&#30784;&#25968;&#20540;&#31867;&#22411;&#30340;&#24615;&#36136;&#30340;&#25509;&#21475;&#12290;<br />
<span class="t-mark">(&#31867;&#27169;&#26495;)</span></td>
</tr>
</table>
</div>
<div class="visualClear"></div>
</div>
</div>
</div>
</body>
</html>
Reference in New Issue View Git Blame Copy Permalink