my %data = (
   c => 3,
   b => 1,
   a => 2,
);

print "Sorted by key...\n";
for my $key (sort keys %data) {
   print "$key : $data{$key}\n";
}

print "Sorted by value...\n";
for my $key (sort { $data{$a} <=> $data{$b} } keys %data) {
   print "$key : $data{$key}\n";
}