in reply to Return value given a key

You title suggest you have a key, and want a value, but your question is actually the other way around.

The answer is that if you want to find a key belonging to a certain value, you should have used a different datastructure. In a hash, keys are unique, values don't have to. The entire point of a hash is to be able to search with keys - if you want to search with the values, you should have used the values as the keys, and the keys as the values.

Perl --((8:>*

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Re^2: Return value given a key
by monarch (Priest) on Nov 22, 2005 at 13:01 UTC
    Or, if you want to speed up looking for a value, build an inverse hash..
      my %forwardhash = (
    key1 => 'value1',
    key2 => 'value2',
    key3 => 'value3'
  );

  my %reversehash = ();
  while ( my ( $key, $value ) = each %forwardhash ) {
      $reversehash{$value} = $key;
  }

  use Data::Dumper;
  print Dumper( \%reversehash );

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    Outputs:

      $VAR1 = {
            'value1' => 'key1',
            'value2' => 'key2',
            'value3' => 'key3'
          };

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