//刪除選訂便當並自動導向

 include_once('Bag.inc');
    session_start();
    
    $_SESSION['bag']->delete_order_item($_GET['lunchbox_number']);
    header("Location:bag_content.php");

//delete_order_item()

function delete_order_item($item_number){
        unset($this->lunchbox_number[$item_number]);
        unset($this->lunchbox_name[$item_number]);
        unset($this->single_cost[$item_number]);
        unset($this->quantity[$item_number]);
        unset($this->price[$item_number]);
        $this->total_cost = array_sum($this->price);
    }