Calculator::div PHP 메소드

    public function div($a, $b)
    {
        return $a / $b;
    }

    }
    function div()
    {
        $this->result = $this->fristnumb / $this->nextnumb;
        echo $this->result;
    }
}
$num1 = $_POST['num1'];
$num2 = $_POST['num2'];
$char = $_POST['char'];
switch ($char) {
    case '+':
        $add = new Calculator($num1, $num2);
        $add->add();
        break;
    case '-':
        $sub = new Calculator($num1, $num2);
        $sub->sub();
        break;
    case '*':
        $mul = new Calculator($num1, $num2);
        $mul->mul();
        break;
    case '/':
        $div = new Calculator($num1, $num2);
        $div->div();
        break;
    default:
        echo "输入有误";
        break;
}