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$hash{a} = 0; $hash{b} = 1; $hash{c} = 0; $hash{d} = 3;
a = 0 c = 0 b = 1 d = 3
c = 0 a = 0 b = 1 d = 3
foreach my $k ( sort { $hash{$a} <=> $hash{$b} } keys %hash ) { print "$k = $hash{$k}\n"; }