In addition to what Zaxo tells you, you could also do a freshmeat search for "hash."

Just a quick vocabulary session - an indexed array is that data structure which is directly accessed by its position within the array (by an integer - array[0] array[1] etc). an associatve array, or hash or key-value pair, is that data structure which is directly (or indirectly but definetly position independent) accessed by its "key" (by a string - hash{"monks"}).

If you go the freshmeat route, search for "hash" be sure to seperate the hash algorithm stuff (MD5, SHA-1, shash, etc) from the hash data structure stuff (glibc, libdict, ght, etc) - they're slightly related but different beasties.

-derby