Date::Manip is able to parse a wide variety of date formats automatically. There's half the assignment, already done.

I can't remember if Date::Manip is a core module or not. If not, you can download it from CPAN, or if you're an ActiveState user, just pull it in with PPM.

From the Date Manip POD:

In the documentation below, US formats are used, but in most (if not all) cases, a non-English equivalent will work equally well.

1. Parsing a date from any convenient format

  $date = ParseDate("today");
  $date = ParseDate("1st thursday in June 1992");
  $date = ParseDate("05/10/93");
  $date = ParseDate("12:30 Dec 12th 1880");
  $date = ParseDate("8:00pm december tenth");
  if (! $date) {
    # Error in the date
  }
[download]

Even if you're not allowed to use the Date::Manip module, at least look at its source code so you can see how it does all those neat tricks!

I wish I was allowed to use it...although the assignment doesn't explicitly say I can't...Hmmmmm.

I surfed over there earlier today, and looked at the source. Sadly my brain still hurts from that - it was kinda like not closing my eyes while opening the ark, ya know? ;-)

I provide this because, quite simply, I'm sure you'd not be allowed to use it! However it's really the easiest solution to the problem:

package DateTime::Format::Homework;
use DateTime::Format::Builder (
    parsers => {
        parse_datetime => [
            {strptime => '%b %d %Y'}, # Apr 8 1984
            {strptime => '%b %d %y'}, # Apr 08 84
            {strptime => '%m/%d/%y'}, # 4/8/84 and 04/08/84
            {strptime => '%d %b %Y'}, # 08 Apr 1984
        ],
    }
);
[download]

And that's it, you have a parser that will handle all your teacher's dates without you needing to tell the script which kind of date you have. Of course, you can keep on adding strptime parsers until the cows come home and it will still work.*

Now here's how to use it:

use DateTime::Format::Homework;

foreach ('Apr 8 1984', 'Apr 08 84', '4/8/84', '04/08/84', '08 Apr 1984
+') {
    print DateTime::Format::Homework->parse_datetime( $_ )->ymd . "\n"
+;
}
[download]

1984-04-08
1984-04-08
1984-04-08
1984-04-08
1984-04-08
[download]

to read date formats as follows - Apr 8 1984, Apr 08 84, 4/8/84, 04/08/84, and 08 Apr 1984

• Take a close look at these date formats, what are the differences and what is similar? Each date format consists of three parts, separated either by space or by '/'. Take a look at split.
• The year is always the last field, so that's easy. Just make sure that you add 1900 to it whenever it's necessary.
• The month comes either as an abbreviation containing letters or as a number. Check which is true and act accordingly. For the mapping from 'Apr' to 4, a hash is ideal. For the output in a different format you probably need the reverse mapping.
• Write one subroutine for reading in the date and return it in a standard format, e.g. three numbers for year (4 digit), month and day. Maybe add some date validation for extra credits :).
• Then write conversions from this 'standard' format into all necessary output formats. See sprintf.
• At last, when you are finished or get stuck, let us know what you have, I'm sure we can give a few more valulabe tips.

Many thanks to all. I'll start hacking on some code tonight and post it if I get stuck...or post it if I get it right on my own. (as if! :-)

Again, thanks!

As this is homework, I'm hesitant to provide (pseudo) code. ;-) There are a number of ways to go about this, like using a big if/elsif block to match the right format. Also, you probably need some sort of lookup table for the months.

Arjen

LOL...all that, huh? (not to forget the shebang) You make it sound so easy! ;-) thanks :)