use strict;
use warnings;

my %items = (dog => 20, desk => 10, cow => 150);

print "By name:\n";
print "$_: $items{$_}\n" for sort {$a cmp $b} keys %items;

print "\nBy weight:\n";
print "$_: $items{$_}\n" for sort {$items{$a} <=> $items{$b}} keys %items;