difftime(3) Library Functions Manual difftime(3)
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 at-
tributes(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 de-
fine
#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)
Linux man-pages 6.03 2022-12-29 difftime(3)
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