Section: Linux Programmer's Manual (3)
timegm, timelocal - inverses of gmtime and localtime
time_t timelocal(struct tm *tm);
time_t timegm(struct tm *tm);
Feature Test Macro Requirements for glibc (see
Since glibc 2.19:
Glibc 2.19 and earlier:
_BSD_SOURCE || _SVID_SOURCE
are the inverses of
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
takes the local timezone into account when doing the conversion, while
takes the input value to be Coordinated Universal Time (UTC).
these functions return the calendar time (seconds since the Epoch),
expressed as a value of type
On error, they return the value
to indicate the cause of the error.
The result cannot be represented.
For an explanation of the terms used in this section, see
||Thread safety||MT-Safe env locale|
These functions are nonstandard GNU extensions
that are also present on the BSDs.
Avoid their use.
function is equivalent to the POSIX standard function
There is no reason to ever use it.
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