static void Main(string[] args) { string defaultBankAccount = "5620092134961"; //string userInput2 = "159030-776"; // 159030-776, 101710-122 Console.WriteLine("Enter your bank number, ty. (e.g. 562009-2134961, 159030-776)"); string userInput = Console.ReadLine(); if (String.IsNullOrEmpty(userInput)) { userInput = defaultBankAccount; } Bban bban = new Bban(userInput); Console.WriteLine("BBAN is: {0}", bban.ToString()); Iban iban = new Iban(userInput); Console.WriteLine("IBAN is: {0}", iban.ToString()); string newIban = "FI2056200920134961"; if (Iban.Validate(newIban)) { Console.WriteLine($"{newIban} is valid."); } else { Console.WriteLine($"{newIban} is invalid."); } Console.WriteLine(Iban.GetBicCode(iban.ToString())); // END Console.WriteLine("\nPress any key to continue...."); Console.ReadKey(); }