TIMEGM
Section: Linux Programmer's Manual (3)
Updated: 2016-12-12
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NAME
timegm, timelocal - inverses of gmtime and localtime
SYNOPSIS
#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
DESCRIPTION
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).
RETURN VALUE
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.
ERRORS
- EOVERFLOW
-
The result cannot be represented.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
timelocal(),
timegm()
| Thread safety | MT-Safe env locale
|
CONFORMING TO
These functions are nonstandard GNU extensions
that are also present on the BSDs.
Avoid their use.
NOTES
The
timelocal()
function is equivalent to the POSIX standard function
mktime(3).
There is no reason to ever use it.
SEE ALSO
gmtime(3),
localtime(3),
mktime(3),
tzset(3)
COLOPHON
This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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