static void Main(string[] args) { Client cli1 = new Client("1", "Mark"); Client cli2 = new Client("2", "Coco"); Client cli3 = new Client("3", "Jackson"); Goods apple = new Goods("1", "Apple", 1.5); Goods milk = new Goods("2", "Milk", 3.0); Goods bed = new Goods("3", "Bed", 200); OrderDetails pro1 = new OrderDetails("1", 4, apple); OrderDetails pro2 = new OrderDetails("2", 2, milk); OrderDetails pro3 = new OrderDetails("3", 1, bed); Order ord1 = new Order("0001", cli1); Order ord2 = new Order("0002", cli2); Order ord3 = new Order("0003", cli3); ord1.AddProduct(pro1); ord1.AddProduct(pro2); ord1.AddProduct(pro3); ord2.AddProduct(pro1); ord2.AddProduct(pro3); ord3.AddProduct(pro3); OrderService os = new OrderService(); os.orderlist.Add(ord1); os.orderlist.Add(ord2); List <Order> norder1 = os.AddOrder("0002", cli2); foreach (Order order in norder1) { Console.WriteLine("OrderNumber : " + order.Id + "ClientName : " + order.client.name); } List <Order> norder2 = os.DeleteOrder(ord2); foreach (Order order in norder2) { Console.WriteLine("OrderNumber : " + order.Id + "ClientName : " + order.client.name); } Order norder3 = os.FindOrderByNumber("0003"); Console.WriteLine("OrderNumber : " + norder3.Id + "ClientName : " + norder3.client.name); }