checkValidCreditCardNumber static method
Check if string is a valid credit card number
cardNumber - The credit card number to validate
Returns true if credit card number is valid
Implementation
static bool checkValidCreditCardNumber(String cardNumber) {
// Remove all non-digit characters
final digitsOnly = cardNumber.replaceAll(RegExp(r'[^\d]'), '');
// Credit card should be 13-19 digits
if (digitsOnly.length < 13 || digitsOnly.length > 19) return false;
// Luhn algorithm validation
return _luhnCheck(digitsOnly);
}