Reversing Time

Only Superman can reverse time, unless you know of some other way to fly around the earth and make it rotate backwards around its axis. I thought not. Perl can't reverse time either, but it can understand time that is written in the reverse -- that is, the conversion of hours, minutes, seconds, and so forth into epoch time, rather than the other way around.

The standard Perl distribution also includes the module Time::Local. Using this module, you can calculate the epoch time by supplying the seconds, minutes, hours, day of month, month, and year for a given date.

use Time::Local;

$someday=timelocal(0,30,10,15,2,99);
print scalar localtime($someday);

Yields:

Mon Mar 15 10:30:00 1999

This is nice, but we haven't really solved our initial problem: writing the time in epoch seconds isn't comfortable, but neither is writing the time as broken down into seconds, hours, minutes, day of month, and so on. To tell you what we want -- what we really, really want -- is a way to move between human friendly dates such as "April 25, 1985" and epoch seconds. On its lonesome, Perl is not capable of this acrobatic feat out-of-the-box, so we must turn to a Perl module.

Chopped Time
The Perl You Need to Know
Date::Manip Gymnastics