#!/usr/bin/env perl
my (@months) = qw(APR12 MAR13 APR11 MAR12 FEB13 APR13);

my @mon = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
my $mon;

@{$mon}{@mon} = ( 0 .. $#mon );

sub by_month {
$mon->{$a} <=> $mon->{$b};
}
@months = ( sort by_month @months );
print "@months\n";