How do I check to see if a value in a hash is equal to something?

[Anonymous Monk]

Something of this nature:

  if ((a value from %hash) eq "Superman"){
    do something..;
  }

[ZZamboni]

One way would be by inverting the hash and looking things up by value, as described in perlman:perlfaq4 (see How do I look up a hash element by value?).

Another way, of you are only interested in knowing if the value is in the hash, without knowing the key, could be:

$is_in_hash=grep /^Superman$/,values(%hash);

This is not particularly space efficient if the hash is large. See also the second solution suggested in the FAQ mentioned above.

--ZZamboni

[merlyn]

It has been said:

Another way, of you are only interested in knowing if the value is in the hash, without knowing the key, could be:

$is_in_hash=grep /^Superman$/,values(%hash);

This is not particularly space efficient if the hash is large. See also the second solution suggested in the FAQ mentioned above.

Rather than using a regular expression, just use an ordinary expression:

$is_in_hash = 0 < grep $_ eq "Superman", values %hash;

-- Randal L. Schwartz, Perl hacker