timegm(3) — Linux manual page


TIMEGM(3)                 Linux Programmer's Manual                TIMEGM(3)

NAME         top

       timegm, timelocal - inverses of gmtime and localtime

SYNOPSIS         top

       #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:
           Glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       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         top

       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         top

              The result cannot be represented.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface             Attribute     Value              │
       │timelocal(), timegm() │ Thread safety │ MT-Safe env locale │

CONFORMING TO         top

       These functions are nonstandard GNU extensions that are also present
       on the BSDs.  Avoid their use.

NOTES         top

       The timelocal() function is equivalent to the POSIX standard function
       mktime(3).  There is no reason to ever use it.

SEE ALSO         top

       gmtime(3), localtime(3), mktime(3), tzset(3)

COLOPHON         top

       This page is part of release 5.08 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

GNU                              2016-12-12                        TIMEGM(3)

Pages that refer to this page: asctime(3)asctime_r(3)ctime(3)ctime_r(3)gmtime(3)gmtime_r(3)localtime(3)localtime_r(3)mktime(3)