TAC has asked for the wisdom of the Perl Monks concerning the following question:

Is there a way to traverse nested hashes in search of a particular value without sitting in for loop and looping through the keys?

Edit ar0n 2001-07-13 -- changed title, previously had the ever so descriptive title "Help"

Replies are listed 'Best First'.
Re: Traversing a nested hash
by dragonchild (Archbishop) on Jul 13, 2001 at 21:51 UTC
    So, you're looking for code that doesn't look like: 

    # $hash_ref is passed in and defined outside
# $key_to_find is what we want to find.
# We will return the value of the first $key_to_find
sub traverse_funky_hash {
    my ($hash_ref, $key_to_find) = @_;

    HASH_LOOP:
    foreach (sort keys %$hash_ref) {
        if ($_ eq $key_to_find) {
            return ($hash_ref->{$_}, 1);
        }

        next HASH_LOOP unless ref($hash_ref->{$_} eq 'HASH');
        my ($val, $rc) = traverse_funky_hash($hash_ref->{$_}, $key_to_
+find);
        return ($val, $rc) if $rc;
    }

    return (undef, 0);
}

    [download]

    Obviously, that's for an arbitrarily-nested hash of hashes. (And, yes, I know I'm using ref. Sue me. *grins*)

    Somehow, you want to make it so that you don't have to use the foreach over keys, right?

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Re: Traversing a nested hash
by suaveant (Parson) on Jul 13, 2001 at 21:49 UTC
    Probably, but a for loop is probably the best way... if you know every value is a hash ref in a hash you could do 
    for(values %foo) {
  ...
}

    [download]
    but then you won't know what your key is... what is wrong with a for? Gives us a small example of what you are looking to do.

                    - Ant

[reply]
[d/l]

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