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).

Interface Attribute Value
difftime() Thread safety MT-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)


This page is part of release 5.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Referenced By

ctime(3), jctime(3).

2015-08-08 GNU Linux Programmer's Manual