#!/usr/bin/perl
use strict;
use warnings;
my %Pattern =   ( '(\d{1,2})([-\/.])(\d{1,2})\2(\d{2})' => 'MM%sDD%sRR',
                  '(\d{1,2})([-\/.])(\d{1,2})\2(\d{4})' => 'MM%sDD%sYYYY',
                  '(\d{4})([-\/.])(\d{1,2})\2(\d{1,2})' => 'YYYY%sMM%sDD'
                );

sub ChooseDateFmt($)
{
my $datestr = shift or die;

for my $p (keys %Pattern)
        { return sprintf($Pattern{$p}, $2, $2) if $datestr =~ /^\s*$p\s*$/; }
}

while (<DATA>)
        {
        chomp;
        print "Date\t$_\tFormat=" . ChooseDateFmt($_) . "\n";
        }

__DATA__
10/15/2006
2006/11/01
11/01/06
2006.11.01
11-01-06