man-pages/man3/difftime.3.html
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<H1>DIFFTIME</H1>
Section: Linux Programmer's Manual (3)<BR>Updated: 2015-08-08<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
difftime - calculate time difference
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<PRE>
<B>#include &lt;<A HREF="file:///usr/include/time.h">time.h</A>&gt;</B>
<B>double difftime(time_t </B><I>time1</I><B>, time_t </B><I>time0</I><B>);</B>
</PRE>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
The
<B>difftime</B>()
function returns the number of seconds elapsed
between time <I>time1</I> and time <I>time0</I>, represented as a
<I>double</I>.
Each of the times is specified in calendar time, which means its
value is a measurement (in seconds) relative to the
Epoch, 1970-01-01 00:00:00 +0000 (UTC).
<A NAME="lbAE">&nbsp;</A>
<H2>ATTRIBUTES</H2>
For an explanation of the terms used in this section, see
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
<TABLE BORDER>
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
<TR VALIGN=top><TD>
<B>difftime</B>()
</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
</TABLE>
<A NAME="lbAF">&nbsp;</A>
<H2>CONFORMING TO</H2>
POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.
<A NAME="lbAG">&nbsp;</A>
<H2>NOTES</H2>
On a POSIX system,
<I>time_t</I>
is an arithmetic type, and one could just
define
<P>
#define difftime(t1,t0) (double)(t1 - t0)
<P>
when the possible overflow in the subtraction is not a concern.
<A NAME="lbAH">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?1+date">date</A></B>(1),
<B><A HREF="/cgi-bin/man/man2html?2+gettimeofday">gettimeofday</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+time">time</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?3+ctime">ctime</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+gmtime">gmtime</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+localtime">localtime</A></B>(3)
<A NAME="lbAI">&nbsp;</A>
<H2>COLOPHON</H2>
This page is part of release 5.05 of the Linux
<I>man-pages</I>
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="1"><A HREF="#lbAB">NAME</A><DD>
<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="4"><A HREF="#lbAE">ATTRIBUTES</A><DD>
<DT id="5"><A HREF="#lbAF">CONFORMING TO</A><DD>
<DT id="6"><A HREF="#lbAG">NOTES</A><DD>
<DT id="7"><A HREF="#lbAH">SEE ALSO</A><DD>
<DT id="8"><A HREF="#lbAI">COLOPHON</A><DD>
</DL>
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