NAME

       difftime - calculate time difference

LIBRARY

       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 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).

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │difftime()                                                     │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD.

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.

SEE ALSO

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