141 lines
4.3 KiB
HTML
141 lines
4.3 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta name="generator" content="HTML Tidy, see www.w3.org">
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 -->
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>nan</title>
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</head>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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</script>
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<basefont size="3"> <a name="nan"></a> <a name="tag_03_401"></a><!-- nan -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_401_01"></a>NAME</h4>
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<blockquote>nan, nanf, nanl - return quiet NaN</blockquote>
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<h4><a name="tag_03_401_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/math.h.html">math.h</a>><br>
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<br>
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double nan(const char *</tt><i>tagp</i><tt>);<br>
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float nanf(const char *</tt><i>tagp</i><tt>);<br>
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long double nanl(const char *</tt><i>tagp</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_401_03"></a>DESCRIPTION</h4>
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<blockquote>
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<div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"
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border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the
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requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to
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the ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div>
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<p>The function call <i>nan</i>("<i>n-char-sequence</i>") shall be equivalent to:</p>
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<pre>
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<tt>strtod("NAN(</tt><i>n-char-sequence</i><tt>)", (char **) NULL);
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</tt>
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</pre>
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<p>The function call <i>nan</i>("") shall be equivalent to:</p>
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<pre>
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<tt>strtod("NAN()", (char **) NULL)
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</tt>
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</pre>
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<p>If <i>tagp</i> does not point to an <i>n</i>- <b>char</b> sequence or an empty string, the function call shall be equivalent
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to:</p>
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<pre>
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<tt>strtod("NAN", (char **) NULL)
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</tt>
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</pre>
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<p>Function calls to <i>nanf</i>() and <i>nanl</i>() are equivalent to the corresponding function calls to <a href=
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"../functions/strtof.html"><i>strtof</i>()</a> and <a href="../functions/strtold.html"><i>strtold</i>()</a>.</p>
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</blockquote>
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<h4><a name="tag_03_401_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>These functions shall return a quiet NaN, if available, with content indicated through <i>tagp</i>.</p>
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<p>If the implementation does not support quiet NaNs, these functions shall return zero.</p>
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</blockquote>
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<h4><a name="tag_03_401_05"></a>ERRORS</h4>
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<blockquote>
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<p>No errors are defined.</p>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_401_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_401_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_401_08"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_401_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_401_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="strtod.html"><i>strtod</i>()</a> , <a href="strtold.html"><i>strtold</i>()</a> , the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/math.h.html"><i><math.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_401_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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