// Function: get_sanitized_number
// Description: Returns sanitized version of card number.
// Uses Functions: get_corrected_number
// Parameters: Number to be sanitized.
// Pre-Conditions: Valid card number.
// Post-Conditions: Number retains first 5 digits then is all zeros, except for the check digit at the end that will pass the Luhn Algorithm.
// Return: Sanitized number.
public static ulong get_sanitized_number(ulong num)
{
ulong returnNum = 0;
int checkDigit = CardFunctions.get_last_digit(num);
int[] digits = num.ToString().Select(Convert.ToInt32).ToArray(); // Convert num into array of digits.
for (int i = 0; i < 5; i++) // Retain first 5 digits of the number, and zero the rest.
{
digits[i] -= 48;
returnNum += Convert.ToUInt64(digits[i]) * Convert.ToUInt64(Math.Pow(10, digits.Length - i - 1));
}
return(get_corrected_number(returnNum)); // Return number with the correct check digit at the end.
}
// Function: get_response_string
// Description: Returns response to inputted card number.
// Uses Functions:
// Parameters: Card number entry.
// Pre-Conditions: String
// Post-Conditions: Appropriate string response
// Return: Response string.
public static string get_response_string(string input)
{
ulong cardNumber;
bool isNumeric = ulong.TryParse(input, out cardNumber); // Check to see if string can be converted to a number.
if (!isNumeric) // If not a valid number.
{
return("The number you entered is not valid.");
}
else if (!CardFunctions.is_correct_length(cardNumber)) // If number is an incorrect length.
{
return("The number you entered is not a valid length.");
}
else if (CardFunctions.luhn_check(cardNumber)) // If number does not pass luhn's algorithm.
{
return("The number you entered does not pass the luhn algorithm. \nMaybe you meant to type " + CardFunctions.get_corrected_number(cardNumber).ToString() + "?");
}
else
{
return("The number you entered is a valid card number!");
}
}