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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title><sys/time.h></title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../../jscript/dotcode.js"></script><basefont size="3"> <a name="<sys/time.h>"></a> <a name="tag_13_64"></a><!-- <sys/time.h> --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_13_64_01"></a>NAME</h4><blockquote>sys/time.h - time types</blockquote><h4><a name="tag_13_64_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../../images/opt-start.gif" alt="[Option Start]" border="0"> #include <sys/time.h> <img src="../../images/opt-end.gif" alt="[Option End]" border="0"></tt></div></blockquote><h4><a name="tag_13_64_03"></a>DESCRIPTION</h4><blockquote><p>The <i><sys/time.h></i> header shall define the <b>timeval</b> structure that includes at least the following members:</p><pre><tt>time_t tv_sec </tt> Seconds. <tt>suseconds_t tv_usec </tt> Microseconds. <tt></tt></pre><p>The <i><sys/time.h></i> header shall define the <b>itimerval</b> structure that includes at least the followingmembers:</p><pre><tt>struct timeval it_interval</tt> Timer interval. <tt>struct timeval it_value </tt> Current value. <tt></tt></pre><p>The <b>time_t</b> and <b>suseconds_t</b> types shall be defined as described in <a href="../sys/types.h.html#tag_13_67"><i><sys/types.h></i></a> .</p><p>The <b>fd_set</b> type shall be defined as described in <a href="../sys/select.h.html#tag_13_58"><i><sys/select.h></i></a>.</p><p>The <i><sys/time.h></i> header shall define the following values for the <i>which</i> argument of <a href="../../functions/getitimer.html"><i>getitimer</i>()</a> and <a href="../../functions/setitimer.html"><i>setitimer</i>()</a>:</p><dl compact><dt>ITIMER_REAL</dt><dd>Decrements in real time.</dd><dt>ITIMER_VIRTUAL</dt><dd>Decrements in process virtual time.</dd><dt>ITIMER_PROF</dt><dd>Decrements both in process virtual time and when the system is running on behalf of the process.</dd></dl><p>The following shall be defined as described in <a href="../sys/select.h.html#tag_13_58"><i><sys/select.h></i></a> : <ahref="../../functions/FD_CLR.html"><i>FD_CLR</i>()</a> <a href="../../functions/FD_ISSET.html"><i>FD_ISSET</i>()</a> <a href="../../functions/FD_SET.html"><i>FD_SET</i>()</a> <a href="../../functions/FD_ZERO.html"><i>FD_ZERO</i>()</a> FD_SETSIZE</p><p>The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.</p><pre><tt>int getitimer(int, struct itimerval *);int gettimeofday(struct timeval *restrict, void *restrict);int select(int, fd_set *restrict, fd_set *restrict, fd_set *restrict, struct timeval *restrict);int setitimer(int, const struct itimerval *restrict, struct itimerval *restrict);int utimes(const char *, const struct timeval [2]); (</tt><b>LEGACY</b> <tt>)</tt></pre><p>Inclusion of the <i><sys/time.h></i> header may make visible all symbols from the <a href="../../basedefs/sys/select.h.html"><i><sys/select.h></i></a> header.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_13_64_04"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_64_05"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_64_06"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_13_64_07"></a>SEE ALSO</h4><blockquote><p><a href="../sys/select.h.html#tag_13_58"><i><sys/select.h></i></a> , <a href="../sys/types.h.html#tag_13_67"><i><sys/types.h></i></a> , the System Interfaces volume of IEEE Std 1003.1-2001, <ahref="../../functions/getitimer.html"><i>getitimer</i>()</a>, <a href="../../functions/gettimeofday.html"><i>gettimeofday</i>()</a>, <a href="../../functions/select.html"><i>select</i>()</a>, <a href="../../functions/setitimer.html"><i>setitimer</i>()</a></p></blockquote><h4><a name="tag_13_64_08"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 4, Version 2.</p></blockquote><h4><a name="tag_13_64_09"></a>Issue 5</h4><blockquote><p>The type of <i>tv_usec</i> is changed from <b>long</b> to <b>suseconds_t</b>.</p></blockquote><h4><a name="tag_13_64_10"></a>Issue 6</h4><blockquote><p>The <b>restrict</b> keyword is added to the prototypes for <a href="../../functions/gettimeofday.html"><i>gettimeofday</i>()</a>, <a href="../../functions/select.html"><i>select</i>()</a>, and <ahref="../../functions/setitimer.html"><i>setitimer</i>()</a>.</p><p>The note is added that inclusion of this header may also make symbols visible from <a href="../../basedefs/sys/select.h.html"><i><sys/select.h></i></a>.</p><p>The <a href="../../functions/utimes.html"><i>utimes</i>()</a> function is marked LEGACY.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../../mindex.html">Main Index</a> | <a href="../../basedefs/contents.html">XBD</a> | <a href="../../utilities/contents.html">XCU</a> | <a href="../../functions/contents.html">XSH</a> | <a href="../../xrat/contents.html">XRAT</a> ]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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