how can i get the percentage of difference between two strings?

[the prince Awah]

hi guys, how can i get the difference between two strings in PHP?
i mean lets say string 1 = "hello world"
and string 2 = "Hello World"
the php code should compare these two strings and output something like:
the difference between the two strings is 20%...

so how can i do this???

[pritaeas]

http://www.php.net/manual/en/function.similar-text.php

[diafol]

PHP has a number of functions - as shown by Pritaeas' link, but you need to set rules for the comparison, as it can get quite complicated. Case sensitive - OK. How would you do the following:

"Hello World Says Me" | "I Said Hello My World Hello"

What sort of %age would you return for this with your rules?