php有关问题(急功近利)

$G){
            $file_size = ($file_size / $G)." G";
        }elseif($file_size>$M){
            $file_size = ($file_size / $M) ." M";
        }elseif($file_size > $K){
            $file_size = ($file_size /$K). " K";
        }else{
            $file_size = $file_size. " byte";
        }
        return $file_size;
    }
    echo getFileSize("new_file.html");
?>