. Compare two dates

 $date1 = ParseDate($string1);
 $date2 = ParseDate($string2);
 $flag = Date_Cmp($date1,$date2);
 if ($flag<0) {
   # date1 is earlier
 } elsif ($flag==0) {
   # the two dates are identical
 } else {
   # date2 is earlier
 }

##</code><code>##

Among other things, Date::Manip allow you to:
...
2. Compare two dates, entered in widely different formats to determine
which is earlier