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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>floor</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_110"> </a>NAME</h4><blockquote>floor - floor function</blockquote><h4><a name = "tag_000_005_111"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="math.h.html">math.h</a>>double floor(double <i>x</i>);</code></pre></blockquote><h4><a name = "tag_000_005_112"> </a>DESCRIPTION</h4><blockquote>The<i>floor()</i>function computes the largest integral value not greater than<i>x</i>.<p>An application wishing to check for error situations should set<i>errno</i>to 0 before calling<i>floor()</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_113"> </a>RETURN VALUE</h4><blockquote>Upon successful completion,<i>floor()</i>returns the largest integral value not greater than<i>x</i>,expressed as a<b>double</b>.<p>If<i>x</i>is NaN, NaN is returned and<i>errno</i>may be set to [EDOM].<p>If the correct value would cause overflow, -HUGE_VAL is returned and<i>errno</i>is set to [ERANGE].<p>If<i>x</i>is ±Inf or ±0, the value of<i>x</i>is returned.</blockquote><h4><a name = "tag_000_005_114"> </a>ERRORS</h4><blockquote>The<i>floor()</i>function will fail if:<dl compact><dt>[ERANGE]<dd>The result would cause an overflow.</dl><p>The<i>floor()</i>function may fail if:<dl compact><dt>[EDOM]<dd>The value of<i>x</i>is NaN.</dl><p>No other errors will occur.</blockquote><h4><a name = "tag_000_005_115"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_116"> </a>APPLICATION USAGE</h4><blockquote>The integral value returned by<i>floor()</i>as a<b>double</b>might not be expressible as an<b>int</b>or<b>long int</b>.The return value should be tested before assigning it to aninteger type to avoid the undefined results of an integer overflow.<p>The<i>floor()</i>function can only overflow when the floating pointrepresentation has DBL_MANT_DIG > DBL_MAX_EXP.</blockquote><h4><a name = "tag_000_005_117"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_118"> </a>SEE ALSO</h4><blockquote><i><a href="ceil.html">ceil()</a></i>,<i><a href="isnan.html">isnan()</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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