As already mentioned, the Date::Calc module will do the trick. Specifically, look at the Decode_Date_US and Decode_Date_EU functions for parsing out the day, month, and year. Unless I'm mistaken, though, you'll have to employ something like sprintf to format the date. There is also the check_date function to verify the date is valid.

In the spirit of TMTOWTDI, though, you could also use the Date::Manip module. It has different strengths than Date::Calc, and it might be useful for other projects. Here is how you could do this using Date::Manip:

use strict;
use warnings;

use Date::Manip;

my $rawdate = '10/12/04';

Date_Init( "DateFormat = US" ); # default
munge_date( $rawdate );

Date_Init( "DateFormat = European" );
munge_date( $rawdate );

$rawdate = '32/12/04';
munge_date( $rawdate );

sub munge_date
{
    my ( $rawdate ) = @_;

    my %cfgvars = map { split( '=', $_ ) } Date_Init();

    print "DateFormat is set to $cfgvars{DateFormat}, ",
          "parsing $rawdate:\n";

    my $date = DateCalc( $rawdate, "+ 1 week" );

    if( not defined $date )
    {
        print "   $rawdate is not a valid date\n";
        return;
    }

    print '   orig date = ', UnixDate( $rawdate, "%b %e, %Y" ), "\n";
    print '   + 1 week  = ', UnixDate( $date, "%m/%d/%y" ),
          " (mm/dd/yy)\n";
    print '               ', UnixDate( $date, "%d/%m/%y" ),
          " (dd/mm/yy)\n";
    print '               ', UnixDate( $date, "%Y-%m-%d" ),
          " (yyyy-mm-dd)\n";
}

** OUTPUT **

DateFormat is set to US, parsing 10/12/04:
   orig date = Oct 12, 2004
   + 1 week  = 10/19/04 (mm/dd/yy)
               19/10/04 (dd/mm/yy)
               2004-10-19 (yyyy-mm-dd)
DateFormat is set to European, parsing 10/12/04:
   orig date = Dec 10, 2004
   + 1 week  = 12/17/04 (mm/dd/yy)
               17/12/04 (dd/mm/yy)
               2004-12-17 (yyyy-mm-dd)
DateFormat is set to European, parsing 32/12/04:
   32/12/04 is not a valid date
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