As mentioned elsewhere, you can use recursion: 
sub foo
{
    my ($hash, @path) = @_;
    while (my ($k, $v) = each %$hash) {
        if (ref $v eq 'HASH') {
            foo($v, @path, $k);
        } else {
            # whatever
        }
    }
}

[download]
You can also use "eval" to build up the loops (hand-waving a bit): 
$depth = compute_hash_depth;
$code = '...';
for (reverse 1..$depth) {
    my $prev = $_-1;
    $code = "while (my (\$k$_, \$v$_) = each \$v$prev) { $code }";
}
eval $code;

[download]
In general, when you want nested loops and don't know how many beforehand, recursion is easiest.

In reply to Re: Dynamically create a foreach loop within a foreach loop? by educated_foo
in thread Dynamically create a foreach loop within a foreach loop? by jdlev

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