gbarr has given us Date::Parse so that we do not need to do this sort of thing (splitting dates that is). (Date::Manip would work too but it's a bit big for such a simple project.)

#!/usr/bin/perl
use strict;
use Date::Parse;
my $string = "9/1/2001";
my ($day,$month,$year) = (strptime($string))[3..5];
$month++;
$year+=1900;
my $new_date = join('-', $year, $month, $day);
print $new_date,$/;
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