isCreditCard function

bool isCreditCard (
  1. String str
)

check if the string is a credit card

Implementation

bool isCreditCard(String str) {
  String sanitized = str.replaceAll(new RegExp(r'[^0-9]+'), '');
  if (!_creditCard.hasMatch(sanitized)) {
    return false;
  }

  // Luhn algorithm
  int sum = 0;
  String digit;
  bool shouldDouble = false;

  for (int i = sanitized.length - 1; i >= 0; i--) {
    digit = sanitized.substring(i, (i + 1));
    int tmpNum = int.parse(digit);

    if (shouldDouble == true) {
      tmpNum *= 2;
      if (tmpNum >= 10) {
        sum += ((tmpNum % 10) + 1);
      } else {
        sum += tmpNum;
      }
    } else {
      sum += tmpNum;
    }
    shouldDouble = !shouldDouble;
  }

  return (sum % 10 == 0);
}