static void Main(string[] args) { ManageBook Man = new ManageBook(); string ID; int input = 0; do { Clear(); WriteLine("***Welcome to Book Library System***"); WriteLine("1.Add new book"); WriteLine("2.Update book"); WriteLine("3.Delete Book"); WriteLine("4.Show all Book"); WriteLine("5.Quit"); Write("Choose: "); input = Validation.CheckInput(); switch (input) { //Add New book case 1: WriteLine("***Add new book***"); Man.AddNewBook(); ReadLine(); break; //Update Book case 2: WriteLine("***Update book by ID***"); Write("Enter ID: "); ID = Console.ReadLine(); Man.UpdateBook(ID); ReadLine(); break; //Delete Book case 3: WriteLine("***Delete Book by ID***"); Write("Enter ID: "); ID = Console.ReadLine(); Man.DeleteBook(ID); ReadLine(); break; //Show all Book case 4: WriteLine("***Show all Book***"); Man.ShowAll(); ReadLine(); break; case 5: WriteLine("Goodbye"); ReadLine(); break; default: WriteLine("Invalid Choice!"); ReadLine(); break; } } while (input != 5); }