difftime(3) - Linux man page
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. The two times are specified in calendar time, which represents the time elapsed since the Epoch (00:00:00 on
January 1, 1970, Coordinated Universal Time (UTC)).
Conforming to
SVr4, 4.3BSD, 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.
Conforming to
SVr4, 4.3BSD, POSIX.1-2001.
See Also
date(1),
gettimeofday(2),
time(2),
ctime(3),
gmtime(3),
localtime(3)
