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

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