difftime(3)
NAME
difftime - calculate time difference
SYNOPSIS
#include <time.h> double difftime(time_t time1, time_t time0);
DESCRIPTION
The difftime() function returns the number of seconds elapsed between
time time1 and time time0, represented as a double. 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).
CONFORMING TO
SVr4, 4.3BSD, C89, C99.
NOTES
- On a POSIX system, time_t is an arithmetic type, and one could just
define
- #define difftime(t1,t0) (double)(t1 - t0)
- when the possible overflow in the subtraction is not a concern. On other systems, the data type time_t might use some other encoding where subtraction doesn't work directly.
SEE ALSO
date(1), gettimeofday(2), time(2), ctime(3), gmtime(3), localtime(3)
COLOPHON
- This page is part of release 3.25 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.