OFFTIME(3)

NAME
offtime, offtime_r, timeoff, timegm, timelocal - convert date and time

LIBRARY
libc

SYNOPSIS
#include <time.h>
struct tm *
offtime(const time_t * clock, long int offset);
struct tm *
offtime_r(const time_t * clock, long int offset, struct tm *ret);
time_t
timeoff(struct tm * tm, long int offset);
time_t
timegm(struct tm * tm);
time_t
timelocal(struct tm * tm);

DESCRIPTION
These functions are inspired by C standard interfaces named similarly.

offtime() converts the calendar time clock, offset by offset seconds, into broken-down time, expressed as Coordinated Universal Time (UTC).

offtime_r() is similar to offtime() but it places the returned struct tm * in the user supplied ret argument.

timeoff() converts the broken-down time tm, expressed as UTC, offset by offset seconds, into a calendar time value.

timegm() converts the broken-down time tm into a calendar time value, effectively being the inverse of gmtime(3). It is equivalent to the C standard function mktime(3) operating in UTC.

timelocal() converts the broken down time tm, expressed as local time, into a calendar time value. It is equivalent to the C standard function mktime(3), and is provided for symmetry only.

SEE ALSO
ctime(3), tm(3), tzset(3)

STANDARDS
The timegm() function conforms to isoC-2023.