Function.utf8 clean string

utf8_clean_string –– Clean-up a string

Description
Makes a clean string of $text. This function is used to generate a "clean" version of the input string.
 * 1) string utf8_clean_string($text)

Clean means that it is a case insensitive form (case folding) and that it is normalized (NFC). Additionally a homographs of one character are transformed into one specific character (preferably ASCII if it is an ASCII character).

Return Values
Cleaned up version of the input string

Note
Please be aware that if you change something within this function or within functions used here you need to rebuild/update the username_clean column in the users table. And all other columns that store a clean string otherwise you will break this functionality.

Example #1
This just explains the function. But is nothing from the phpbb code itself. echo utf8_clean_string("Fo0b4R"); which returns "fo0b4r"

Function.utf8_clean_string