http://www.perlmonks.org?node_id=541351


in reply to help needed in retrieving the hash key

An alternative method uses the each and keys functions to iterate over a hash and locate the keys. This has the advantage of coping with the more general case wher multiple instances of a value in addition to not requiring the storage of another hash.
my @keys = qw ( a b c d e f g h i j); my @vals = qw ( 1 1 1 4 5 6 7 8 9 0); my %hash; @hash{@keys} = @vals; my @ones = grep {(each %hash)[1] == 1} keys %hash; print "@ones\n";

Inverting the hash as shown previously is a better method if you are OK with the storage overhead and you will be doing multiple retrievals.