centos man page for difftime

DIFFTIME(3)						     Linux Programmer's Manual						       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.

SEE ALSO
       date(1), gettimeofday(2), time(2), ctime(3), gmtime(3), localtime(3)

COLOPHON
       This  page is part of release 3.53 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/.

GNU
								    2012-12-22							       DIFFTIME(3)