public void Execute(CarDealer dealer) { double low, high; while (true) { Console.Write("Specify lowest price: "); string input = Console.ReadLine(); if (double.TryParse(input, out low)) { break; } } while (true) { Console.Write("Specify highest price: "); string input = Console.ReadLine(); if (double.TryParse(input, out high)) { break; } } (new PrintVehiclesCommand()) .Execute(dealer.SearchVehicleInPriceRange(low, high)); }