Rimuovere i caratteri sporchi da una stringa

function cleanString($string)
{
$string = str_replace(“è”, “e”, $string);
$string = str_replace(“à “, “a”, $string);
$string = str_replace(“à”, “o”, $string);
$string = str_replace(“ì”, “i”, $string);
$string = str_replace(“ù”, “u”, $string);
$string = ereg_replace(“[^A-Za-z0-9 ]“, “”, $string );
return $string;
}