foreach my $key3 (sort keys  %{$hash{$hash{$key1}} }       ){ ... }

This may serve you better (untested):
    foreach my $key3 (sort keys %{ $hash{$key1}{$key2} }) { ... }
Also note that with Perl version 5.14+, keys et al will take a hash reference directly: see  keys EXPR

In reply to Re: Hash with three keys by AnomalousMonk
in thread Hash with three keys by Jeri

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