hello i have problem with my project
public function toUpper($plain){
        $upper = strtoupper($plain);
        $pos = strpos($plain,$upper);
        $length = strlen($plain,$upper);
        if($pos !== false && $pos == 0){
            return $upper.substr($plain, $length);
        }else{
            return $upper.$plain;
        }
    }
and my problem on
$upper = strtoupper($plain);
please help me, thank you
 
     
    