124 lines
3.9 KiB
HTML
124 lines
3.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>atof</title>
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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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<basefont size="3"> <a name="atof"></a> <a name="tag_03_33"></a><!-- atof -->
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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_33_01"></a>NAME</h4>
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<blockquote>atof - convert a string to a double-precision number</blockquote>
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<h4><a name="tag_03_33_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/stdlib.h.html">stdlib.h</a>><br>
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<br>
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double atof(const char *</tt><i>str</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_33_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 call <i>atof</i>(<i>str</i>) shall be equivalent to:</p>
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<pre>
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<tt>strtod(</tt><i>str</i><tt>,(char **)NULL),
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</tt>
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</pre>
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<p>except that the handling of errors may differ. If the value cannot be represented, the behavior is undefined.</p>
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</blockquote>
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<h4><a name="tag_03_33_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>The <i>atof</i>() function shall return the converted value if the value can be represented.</p>
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</blockquote>
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<h4><a name="tag_03_33_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_33_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_33_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The <i>atof</i>() function is subsumed by <a href="../functions/strtod.html"><i>strtod</i>()</a> but is retained because it is
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used extensively in existing code. If the number is not known to be in range, <a href=
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"../functions/strtod.html"><i>strtod</i>()</a> should be used because <i>atof</i>() is not required to perform any error
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checking.</p>
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</blockquote>
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<h4><a name="tag_03_33_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_33_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_33_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="strtod.html"><i>strtod</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/stdlib.h.html"><i><stdlib.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_33_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 1. Derived from Issue 1 of the SVID.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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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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