How to display all keys in a multi-dim array?

Hi all, I am trying to work out how to display all of the keys in a multi-dimensional array (not their values). For example: $array = array(); $array['a'] = "1"; $array['a']['b'] = "2"; $array['a']['b']['c'] = "3"; $array['a']['b']['c']['d'] = "4"; What I need is to be able to somehow print out the values a,b,c and d based on the search result for "4". Is this even possible? Best regards, Richard Davey -- http://www.launchcode.co.uk - PHP Development Services "I am not young enough to know everything." - Oscar Wilde