key_exists from php

There doesn't seem to be any way for a php script to determine whether a given key exists in an array. isset($arr['x']) fails when it exists but has a null value. I know there are ways around it like using foreach or array_keys but these don't seem very efficient. I would like to add a function key_exists, with the following proto: bool key_exists(array search, string key) Please let me know if this is inappropriate or I have missed something obvious, otherwise I shall add this tomorrow. Thanks, David. -- |> /+\ \| | |> David Croft Infotrek