Implement the Luhn Algorithm - Implement the Luhn Algorithm

Python
1

Tell us what’s happening:

I’m unable to satisfy test #6. It works with #7, but not #6. I’m not quite sure what to do next.

Your code so far

import re
findDigex = re.compile(r'\d+')

def verify_card_number(ccn):
    ccn_int = [int(s) for s in findDigex.findall(ccn)] #Extracts all numbers from number to be verified
    digits = [int(digit) for num in ccn_int for digit in str(num)] #separates all numbers into single values within a list
    check_digit = digits[-1] #assigns the check digit
    del digits[-1] #deletes the check digit from the end of digits
    
    number_length = len(digits)


    eval_nums = []
    for index, num in enumerate(digits):
        if number_length % 2 == 1:
            if index % 2 == 0:           
                num = num * 2
                if num >= 10:
                    num = (num // 10) + (num % 10)
            eval_nums.append(num)
        
        if number_length % 2 == 0:
            if index % 2 == 1:           
                num = num * 2
                if num >= 10:
                    num = (num // 10) + (num % 10)
            eval_nums.append(num)
    
    eval_nums.append(check_digit)  #Re-add the check_digit back

    check_sum = sum(eval_nums)

    if check_sum % 10 == 0:
        return 'VALID!'
    else:
        return 'INVALID!'



print(verify_card_number('4111-1111-1111-1111'))
print(verify_card_number('453914889'))

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Challenge Information:

Implement the Luhn Algorithm - Implement the Luhn Algorithm

2

Fixed it. Had to get rid of regex and find a different method to extract digits.
digits = [int(num) for num in ccn if num.isdigit()]
I’m not sure where in the tests it was making a mistake, but all the test cases given it worked. Maybe a number used for an edge case?