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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>frexp</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_005_257"> </a>NAME</h4><blockquote>frexp - extract mantissa and exponent from a double precision number</blockquote><h4><a name = "tag_000_005_258"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="math.h.html">math.h</a>>double frexp(double <i>num</i>, int *<i>exp</i>);</code></pre></blockquote><h4><a name = "tag_000_005_259"> </a>DESCRIPTION</h4><blockquote>The<i>frexp()</i>function breaks a floating-point number into a normalisedfraction and an integral power of 2.It stores the integer exponent in the<b>int</b>object pointed to by<i>exp</i>.<p>An application wishing to check for error situations should set<i>errno</i>to 0 before calling<i>frexp()</i>.If<i>errno</i>is non-zero on return, or the return value is NaN, an error has occurred.</blockquote><h4><a name = "tag_000_005_260"> </a>RETURN VALUE</h4><blockquote>The<i>frexp()</i>function returns the value<i>x</i>,such that<i>x</i>is a<b>double</b>with magnitude in the interval [½, 1) or 0, and<i>num</i>equals<i>x</i>times 2 raised to the power<i>*exp</i>.<p>If<i>num</i>is 0, both parts of the result are 0.<p>If<i>num</i>is NaN, NaN is returned,<i>errno</i>may be set to [EDOM] and the value of<i>*exp</i>is unspecified.<p>If<i>num</i>is ±Inf,<i>num</i>is returned,<i>errno</i>may be set to [EDOM] and the value of<i>*exp</i>is unspecified.</blockquote><h4><a name = "tag_000_005_261"> </a>ERRORS</h4><blockquote>The<i>frexp()</i>function may fail if:<dl compact><dt>[EDOM]<dd>The value of<i>num</i>is NaN or ±Inf.</dl><p>No other errors will occur.</blockquote><h4><a name = "tag_000_005_262"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_263"> </a>APPLICATION USAGE</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_264"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_265"> </a>SEE ALSO</h4><blockquote><i><a href="isnan.html">isnan()</a></i>,<i><a href="ldexp.html">ldexp()</a></i>,<i><a href="modf.html">modf()</a></i>,<i><a href="math.h.html"><math.h></a></i>.</blockquote><h4>DERIVATION</h4><blockquote>Derived from Issue 1 of the SVID.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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