timegm, timelocal - inverses of gmtime and localtime
#include <time.h>
time_t timelocal(struct tm *tm);
time_t timegm(struct tm *tm);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
timelocal(),
timegm():
Since glibc 2.19:
_DEFAULT_SOURCE
Glibc 2.19 and earlier:
_BSD_SOURCE || _SVID_SOURCE
The functions
timelocal() and
timegm() are the inverses of
localtime(3) and
gmtime(3). Both functions take a broken-down
time and convert it to calendar time (seconds since the Epoch, 1970-01-01
00:00:00 +0000, UTC). The difference between the two functions is that
timelocal() takes the local timezone into account when doing the
conversion, while
timegm() takes the input value to be Coordinated
Universal Time (UTC).
On success, these functions return the calendar time (seconds since the Epoch),
expressed as a value of type
time_t. On error, they return the value
(time_t) -1 and set
errno to indicate the cause of the
error.
- EOVERFLOW
- The result cannot be represented.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
timelocal (), timegm () |
Thread safety |
MT-Safe env locale |
These functions are nonstandard GNU extensions that are also present on the
BSDs. Avoid their use.
The
timelocal() function is equivalent to the POSIX standard function
mktime(3). There is no reason to ever use it.
gmtime(3),
localtime(3),
mktime(3),
tzset(3)