difftime - calculate time difference
Standard C library (
libc,
-lc)
#include <time.h>
double difftime(time_t time1, time_t time0);
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).
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
difftime () |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD.
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.
date(1),
gettimeofday(2),
time(2),
ctime(3),
gmtime(3),
localtime(3)