difftime man page

difftime — calculate time difference


#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).

difftime()Thread safetyMT-Safe

Conforming to

POSIX.1-2001, POSIX.1-2008, C89, 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.

See Also

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

Referenced By

ctime(3), jctime(3).

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