Najlaksi i nabrzi nacin je verovatno preko regualrnih izraza:
Code:
$string = preg_replace('/\W/', '', $string);
Ovo ce skloniti sve osim slova, brojeva i underscorea (_). Ukoliko ti bas smeta underscore:
Code:
$string = preg_replace('/[^a-z0-9]/i', '', $string);
Never trust an operating system you don't have sources for.