Yeah, str_split isn't available until version 5. Since I use str_split quite a bit, I just took pretty much what I gave you and made my own str_split function, and stuck it in one of my function include files.
Same thing, just in a function:
function str_split($string) {
$array = array();
for($i=0;$i<strlen($number);$i++) {
$array[] = substr($number,$i,1);
}
return $array;
}