3.2.1. Problem

3.2.2. Solution

use Time::Local;
$TIME = timelocal($sec, $min, $hours, $mday, $mon, $year);
$TIME = timegm($sec, $min, $hours, $mday, $mon, $year);

3.2.3. Discussion

The built-in function localtime converts an Epoch seconds value to distinct DMYHMS values; the timelocal subroutine from the standard Time::Local module converts distinct DMYHMS values to an Epoch seconds value. Here's an example that shows how to find Epoch seconds for a time in the current day. It gets the day, month, and year values from localtime:

# $hours, $minutes, and $seconds represent a time today,
# in the current time zone
use Time::Local;
$time = timelocal($seconds, $minutes, $hours, (localtime)[3,4,5]);

If you're passing month and year values to timelocal, it expects values with the same range as those which localtime returns. Namely, months start at 0, and years have 1900 subtracted from them.

This code illustrates both the use of timegm and how to adjust the ranges of months and years:

# $day is day in month (1-31)
# $month is month in year (1-12)
# $year is four-digit year e.g., 1967
# $hours, $minutes and $seconds represent UTC (GMT) time 
use Time::Local;
$time = timegm($seconds, $minutes, $hours, $day, $month-1, $year-1900);

As explained in the introduction, Epoch seconds cannot hold values before Fri Dec 13 20:45:52 1901 or after Tue Jan 19 03:14:07 2038. Don't convert such dates to Epoch seconds—use a Date:: module from CPAN, and do your calculations with that instead.

3.2.4. See Also