static void Main(string[] args) { int selection = 0; int option = 0; int option2 = 0; do { Console.WriteLine("================Welcome to the store================"); Console.WriteLine("1. Work on products"); Console.WriteLine("2. Work on invoices"); Console.WriteLine("0. Exit"); Console.WriteLine("Select an option, please"); string selectionstr = Console.ReadLine(); while (!int.TryParse(selectionstr, out selection)) { Console.WriteLine("Enter a number, please!"); selectionstr = Console.ReadLine(); } switch (selection) { case 1: do { Console.WriteLine("1. Add product"); Console.WriteLine("2. Edit product"); Console.WriteLine("3. Delete product"); Console.WriteLine("4. Show all the products"); Console.WriteLine("5. Show products by category"); Console.WriteLine("6. Show products by price range"); Console.WriteLine("7. Show products by name"); Console.WriteLine("0. Back"); Console.WriteLine("Select an option, please"); string optionstr = Console.ReadLine(); while (!int.TryParse(optionstr, out option)) { Console.WriteLine("Enter a number, please!"); optionstr = Console.ReadLine(); } switch (option) { case 1: MenuService.AddProductMenu(); break; case 2: MenuService.EditProductMenu(); break; case 3: MenuService.DeleteProduct(); break; case 4: MenuService.DisplayAllProduct(); break; case 5: MenuService.SearchCategoryForProduct2(); break; case 6: MenuService.SearchPriceRangeProduct(); break; case 7: MenuService.SearchNameForProduct(); break; case 0: break; default: Console.WriteLine("There is no such option"); break; } } while (option != 0); break; case 2: do { Console.WriteLine("1. Add invoice"); Console.WriteLine("2. Return invoice"); Console.WriteLine("3. Delete invoice"); Console.WriteLine("4. Show all the invoices"); Console.WriteLine("5. Show invoices by date range"); Console.WriteLine("6. Show invoices by cost range"); Console.WriteLine("7. Show invoice by exact date"); Console.WriteLine("8. Show invoice by number"); Console.WriteLine("0. Back"); Console.WriteLine("Select an option, please"); string optionstr2 = Console.ReadLine(); while (!int.TryParse(optionstr2, out option2)) { Console.WriteLine("Enter a number, please!"); optionstr2 = Console.ReadLine(); } switch (option2) { case 1: MenuService.AddSales(); break; case 2: MenuService.ReturnSales(); break; case 3: MenuService.DeleteSales(); break; case 4: MenuService.DisplayAllSales(); break; case 5: MenuService.DisplayForDateRangeSales(); break; case 6: MenuService.DisplayForPriceRangeSales(); break; case 7: MenuService.DisplayDateSales(); break; case 8: MenuService.DisplaySalesForNo(); break; case 0: break; default: Console.WriteLine("There is no such option"); break; } } while (option2 != 0); break; case 0: Console.WriteLine("Good bye!"); break; default: Console.WriteLine("There is no such option"); break; } } while (selection != 0); }