112 lines
6.4 KiB
HTML
112 lines
6.4 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>NAN</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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</head>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_numeric_math_NAN skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading">NAN</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="https://zh.cppreference.com/w/cpp.html" title="cpp">cpp</a>‎ | <a href="https://zh.cppreference.com/w/cpp/numeric.html" title="cpp/numeric">numeric</a>‎ | <a href="https://zh.cppreference.com/w/cpp/numeric/math.html" title="cpp/numeric/math">math</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dsc-header">
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<td>
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<div>定义于头文件 <code><a href="https://zh.cppreference.com/w/cpp/header/cmath.html" title="cpp/header/cmath"><cmath></a></code></div>
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</td>
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<td></td>
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<td></td>
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</tr>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="co2">#define NAN /*implementation defined*/</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<p>宏 <code>NAN</code> 展开成求值为安静非数（ QNaN ）的 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">float</span></span></span> 类型常量表达式。若实现不支持 QNaN ，则不定义此宏。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p>有许多不同的 NaN 值，区别于其载荷与其符号位。宏 <code>NAN</code> 所生成的 NaN 的载荷与符号位的内容是实现定义的。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="https://zh.cppreference.com/w/cpp/numeric/math/nan.html" title="cpp/numeric/math/nan"><span class="t-lines"><span>nan</span><span>nanf</span><span>nanl</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>非数（NaN）<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="https://zh.cppreference.com/w/cpp/numeric/math/isnan.html" title="cpp/numeric/math/isnan"><span class="t-lines"><span>isnan</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>检查给定的数是否 NaN<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="https://zh.cppreference.com/w/cpp/types/numeric_limits/has_quiet_NaN.html" title="cpp/types/numeric limits/has quiet NaN"><span class="t-lines"><span>has_quiet_NaN</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</span></span></span></div>
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</div>
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</td>
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<td>鉴别能表示特殊值“安静的非数”（ NaN ）的浮点类型<br />
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<span class="t-mark">(<code>std::numeric_limits<T></code> 的公开静态成员常量)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="https://zh.cppreference.com/w/cpp/types/numeric_limits/has_signaling_NaN.html" title="cpp/types/numeric limits/has signaling NaN"><span class="t-lines"><span>has_signaling_NaN</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</span></span></span></div>
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</div>
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</td>
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<td>鉴别能表示特殊值“发信的非数”（ NaN ）的浮点类型<br />
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<span class="t-mark">(<code>std::numeric_limits<T></code> 的公开静态成员常量)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="https://zh.cppreference.com/w/cpp/types/numeric_limits/quiet_NaN.html" title="cpp/types/numeric limits/quiet NaN"><span class="t-lines"><span>quiet_NaN</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</span></span></span></div>
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</div>
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</td>
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<td>返回给定浮点类型的安静 NaN 值<br />
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<span class="t-mark">(<code>std::numeric_limits<T></code> 的公开静态成员函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="https://zh.cppreference.com/w/cpp/types/numeric_limits/signaling_NaN.html" title="cpp/types/numeric limits/signaling NaN"><span class="t-lines"><span>signaling_NaN</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</span></span></span></div>
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</div>
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</td>
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<td>返回给定浮点类型的发信的 NaN<br />
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<span class="t-mark">(<code>std::numeric_limits<T></code> 的公开静态成员函数)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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