preg_match ile karekter kontrolu yapiliyor ben nasil bütün karekterlere izin verebilirim
function validate_name($name, $name_limit, $name_system){
if(preg_match("@ [a-z0-9!'%&/=<>|`/#_\+\*\$\{\[\]\}\^\-]+@i", $name) && strlen($name) <= $name_limit && !ctype_digit($name) && $name !== $name_system && strlen($name) >= 4){
$valid_name = 1;
}
else {
$valid_name = 0;
}
return $valid_name;
}