(PHP 3>= 3.0.7, PHP 4 , PHP 5)
similar_text -- 
     Calculate the similarity between two strings
    
Description
int 
similar_text ( string first, string second [, float percent])
     This calculates the similarity between two strings as described
     in Oliver [1993]. Note that this implementation does not use a
     stack as in Oliver's pseudo code, but recursive calls which may
     or may not speed up the whole process. Note also that the
     complexity of this algorithm is O(N**3) where N is the length of
     the longest string.
    
     By passing a reference as third argument,
     similar_text() will calculate the similarity
     in percent for you. It returns the number of matching chars in
     both strings.