difftime - calculate time difference

NAME  LIBRARY  SYNOPSIS  DESCRIPTION  ATTRIBUTES  STANDARDS  HISTORY  NOTES  SEE ALSO 

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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).

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.

SEE ALSO

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

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