As to the problem at hand, yes, you're going to have to use capturing parens and manipulate the results. Something like the following in your if condition:

if ((($month, $day, $year) = /($month)($day)($year)/io) ||
    (($day, $month, $year) = /($day)($month)($year)/io)) {
....
}
[download]

Then, the question becomes, what goes in the "...."? I'll assume you have a plan in mind for $year, and $day doesn't require anything unless you want to do verification. My suggestion for $month is a hash that looks something like this:

             JANUARY  => 'Jan',
             FEB      => 'Feb',
             FEBRUARY => 'Feb',
             ....
             DEC      => 'Dec',
             DECEMBER => 'Dec');
[download]

Then you can so something like:

printf('%02d-%s-%04d', $day, $mhash{uc $month}, $my_year);
[download]

where $my_year is something you calculated from $year.

Of course, if you want to validate the day first, you could augment %mhash something like this:

my %mhash = (JAN      => {Name => 'Jan', Days => 31},
             ....
[download]

And print like so:

printf('%02d-%s-%04d', $day, $mhash{uc $month}{Name}, $my_year);
[download]

That was probably more answer than you needed, but there ya go.

*Woof*

Actually, I need to amend the above a bit. Looking at your regexes again, I just realized that you'll have to put some capturing parens in them to keep everything happy, and stick undefs in the "if" clause accordingly.

E.g.,

$day = '([0-3]?[0-9])(?:th|st|nd|rd)'
[download]

And in the if, something like:

if ((($month, undef, $day, $year) = /($month)($day)($year)/io) ||
[download]

I didn't go through your regexes and if clauses and give you the exact solution, but I think you get the idea.

*Woof*

In this particular case, you are simply defining $month, $day, and $year, as was done in the original regex. This is good. However, the actual capturing of the values is not done until the regex and the capturing parens should be listed in the regex, not in the variable assignment. Imagine what would happen the first time another programmer (or yourself, several years later) comes along and tries to reuse that code.

print $1 if /(${month}${day}${year})/io;
[download]

print $1 if /${month}${day}(${year})/io;
[download]

The moral of this tale? Make each little snippet of code as generic as possible and when something needs to be done (such as capturing a value to $1), do it where it's being done. Don't hide it somewhere else.

As a side note, I noticed that everyone has dropped the curly braces {} from around the variables. While I will admit that the curly braces are not strictly necessary in the example, I like them for two reasons:

1. If you are used to them, they make the variables stand out (IMHO)
2. In complicated regexes using variable interpolation, they can help to guarantee that the regex compiler is examining the variable you are expecting, rather than pulling in extra characters into your variable name.

Incidentally: Perl-chick's code is from a response to this node.

This is a very good point, Ovid. Sometimes the easiest solution may not be the most maintenable one. In fact, putting the grouping parenthesis in the regex instead of in the variable assignments only adds a little bit of postprocessing. You only need to remove the possible suffixes from $day. So something like this would work:

if (( ($m, $d, $y) = (/($month)($day)($year)/io) ) ||
    ( ($d, $m, $y) = (/($day)($month)($year)/io) ) ) {
        $y += 1900 if $y < 100;
        $m = substr($m, 1, 3);
    $d =~ s/^(\d+).*$/$1/;
        print "$d-$m-$y\n";
}
[download]

Another thing I noticed is that we had been happily assigning the matching strings to the same variables used to hold the regular expressions. Not good. So I renamed the variables in this new code segment.

--ZZamboni

We had been happily assigning the matching strings to the same variables used to hold the regular expressions.

ROTFL!!! I can't stop laughing over this one. Whups!! :)

$month = '(Jan(?:uary)?|Feb(?:ruary)?|Mar(?:ch)?
              |Apr(?:il)?|May|Jun(?:e)?
              |Jul(?:y)?|Aug(?:ust)?|Sep(?:tember)?
              |Oct(?:ober)?|Nov(?:ember)?|Dec(?:ember)?)\s+';
  $day = '([0-3]?[0-9])(?:th|st|nd|rd)?,?\s+'; 
  $year = '([0-9]{2,4})';
[download]

if (( ($month, $day, $year) = (/$month$day$year/io) ) ||
    ( ($day, $month, $year) = (/$day$month$year/io) ) ) {
    $year += 1900 if $year < 100;
    $month = substr($month, 1, 3);
    print "$day-$month-$year\n";
}
[download]

--ZZamboni