Name
difftime - calculate time differenceLibrary
Standard C library ( libc ", " -lc )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 adouble
. 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). Attributes
For an explanation of the terms used in this section, see attributes(7).Interface | Attribute | Value |
T} | Thread safety | MT-Safe |
Standards
C11, POSIX.1-2008.History
POSIX.1-2001, C89, SVr4, 4.3BSD.Notes
On a POSIX system, time_t is an arithmetic type, and one could just define#define my_difftime(t1,t0) (double)(t1 - t0)
when the possible overflow in the subtraction is not a concern.