Uh, not quite. You'll be throwing away any false key ("", "0").

You want:

my @common = grep exists $hash2{$_}, keys %hash1;
my @unique1 = grep !exists $hash2{$_}, keys %hash1;
my @unique2 = grep !exists $hash1{$_}, keys %hash2;
[download]

But if you really want all three at once:

my %t;
$t{$_} .= "1" for keys %hash1;
$t{$_} .= "2" for keys %hash2;
[download]

And then each element of %t will be "1" for 1 only, "2" for 2 only, or "12" for both.

-- Randal L. Schwartz, Perl hacker
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