public boolean isValid(String ccNum) {
	boolean isValid = false;
	int number [] = {};
		
	char ccNumArray [] = ccNum.toCharArray(); 

	//get number as int array; also strip any non-numeric characters out,
	//such as spaces.
	int intArray [] = toIntArray(ccNumArray); //implement method to turn
this into an intarray 

	// reverse the cc number preparatory to checksum calculations
	number = reverse(intArray); //implement method to reverse order
		
	int len = number.length;
	int sum = 0;
	for(int i = 0; i < len; i++) {
		int num = number[i];

		/* this is the checksum digit; it's *never* doubled. Just add
		 * it to the sum
		 */
		if(i == 0) {
			sum += num;
			continue;
		}
		
		/* these are the odd-numbered positions in the array; they
		 * should be doubled, and if the result is > 10, the two digits
		 * should be added together and then added to the sum
		 */
		if(i % 2 != 0) {
			num *=2;
			sum += (num / 10) + (num % 10);
		}

		/* these are the even-numbered positions in the array (except
		 * for position 0). These are never doubled, just added to the
		 * sum
		 */
		else {
			sum += num;
		}
	}
	
	/* if the sum is evenly divisible by 10 (there is no remainder after
	 * the division), then the number is a valid number according to the
	 * luhn algorithm
	 */	
	if(sum % 10 == 0) {
		isValid = true;
	}
	
	return isValid;
}