This one's got me a bit stumped: I'd like to do something like the following:

while(<>) {
   ($a, $b, $c, $d) =~ /(...)(...)(...)(...)/;
   $hash{$a}{$b}{$c}{$d}++;
}
[download]

basically, splitting the line into 3 character chunks and placing them into a multi dimensional hash... however the line could be of arbitrary length, and I'd want to capture all the 3 character sequences (thus the hash could look like: $hash{$a}{$b}{$c}{$d}{$e}{$f}++ or just $hash{$a}++ ) Conversely, how would I read such a datastructure? i.e. if I know the depth of the hash, I can write:

 foreach $key (keys %hash) {
   foreach $key1 (keys %{$hash{$key}}) {
      foreach $key2 (keys %{$hash{$key}{$key1}}) {
      # do something
      }
    }
  }
[download]

But I do not know the depth of the hash.
thanks.