static void Main(string[] args) { Console.WriteLine("Welcome to order management system!"); OrderService server = new OrderService(); while (true) { try { Console.Write("0.help \n1.add order\n2.delete order\n3.show orders\n4.change order information\n5.Search order\n"); int Controler = int.Parse(Console.ReadLine()); switch (Controler) { case 0: break; case 1: server.addOrder(); break; case 2: Console.WriteLine("Please input the ID of the order you want to delete:"); server.delOrder(int.Parse(Console.ReadLine())); break; case 3: server.displayAll(); break; case 4: Console.WriteLine("Please input the ID of the order you want to change"); server.changeOrder(int.Parse(Console.ReadLine())); break; case 5: server.searchOrder(); break; default: break; } } catch { } } }