If your date strings are consistent and simple to break down then you would be able to use the Time::Local module which is a standard part of Perl. The localtime() function turns date values for second, minute etc. into the number of seconds elapsed since the epoch for your particular o/s. Like this

my $epochSecs =
   localtime($secs, $mins, $hours, $mday, $mon, $year);
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Note that $mon is 0 for January to 11 for December.

Once you have converted your three dates to epoch seconds you can do a simple numeric comparison.

If, however, your date strings are complex and inconsistent then using a module as chargrill suggests would probably be less painful.

Cheers,

JohnGG

Update: tag cock-up corrected