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

my @mon = map uc, qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
my $mon;
@{$mon}{@mon} = ( 0 .. $#mon );

sub by_month {
	my ($a_mon, $a_yy) = ($a =~ /(...)(..)/);
	my ($b_mon, $b_yy) = ($b =~ /(...)(..)/);
	$mon->{$a_mon} <=> $mon->{$b_mon};
}

@months = ( sort by_month @months );
print "@months\n";

##</code><code>##

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

my @mon = map uc, qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
my $mon;
@{$mon}{@mon} = ( 0 .. $#mon );

sub by_month {
	my ($a_mon, $a_yy) = ($a =~ /(...)(..)/);
	my ($b_mon, $b_yy) = ($b =~ /(...)(..)/);
	$a_yy <=> $b_yy or $mon->{$a_mon} <=> $mon->{$b_mon};
}

@months = ( sort by_month @months );
print "@months\n";