Name

timegm, timelocal — inverses for gmtime and localtime

Synopsis

#include <time.h>
time_t timelocal( struct tm *  tm);
time_t timegm( struct tm *  tm);

DESCRIPTION

The functions timelocal() and timegm() are the inverses to localtime(3) and gmtime(3).

CONFORMING TO

Not in POSIX.1-2001. Present on the BSDs.

NOTES

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

For a portable version of timegm(), set the TZ environment variable to UTC, call mktime(3) and restore the value of TZ. Something like

#include <time.h>
#include <stdlib.h>

time_t
my_timegm(struct tm *tm)
{
    time_t ret;
    char *tz;

    tz = getenv("TZ");
    setenv("TZ", "", 1);
    tzset();
    ret = mktime(tm);
    if (tz)
        setenv("TZ", tz, 1);
    else
        unsetenv("TZ");
    tzset();
    return ret;
}

SEE ALSO

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


  Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>

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