Debit card

// Debit card program using System; class Submission { // ------------------------- // Subprograms // ------------------------- static bool validate_number(string number_on_card) { bool valid = true; int number_of_characters = number_on_card.Length; if (number_of_characters == 16 || number_of_characters == 19) { foreach (char character in number_on_card) { if (!Char.IsDigit(character) && character != ' ') { valid = false; } } } else { valid = false; } return valid; } static void input_card_details() { bool valid_card = false; string number_input = ""; while (!valid_card) { Console.WriteLine("Enter the 16 digit number:"); number_input = Console.ReadLine(); valid_card = validate_number(number_input); } } // ------------------------- // Main program // ------------------------- public static void Main(string[] args) { input_card_details(); Console.WriteLine("Card details valid."); } }