Originální popis anglicky:
timegm, timelocal - inverses for gmtime and localtime
Návod, kniha: Linux Programmer's Manual
#include <time.h>
time_t timelocal (struct tm *tm);
time_t timegm (struct tm *tm);
The functions
timelocal() and
timegm() are the inverses to
localtime(3) and
gmtime(3).
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() 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;
}
gmtime(3),
localtime(3),
mktime(3),
tzset(3)
