Debug an ISBN Validator - Debug an ISBN Validator

Python
1

Tell us what’s happening:

Just having a problem with none of my isbn’s coming out as valid.

Thanks for the tips.

Your code so far

def validate_isbn(isbn, length):
    if len(isbn) != length:
        print(f'ISBN-{length} code should be {length} digits long.')
        return
    main_digits = isbn[0:length+1]
    print(main_digits)
    given_check_digit = isbn[length-1]
    print(given_check_digit)
    try:
        main_digits_list = [int(digit) for digit in main_digits]
    except ValueError:
        print('Invalid character was found.')
    if length == 10:
        expected_check_digit = calculate_check_digit_10(main_digits_list)
    else:
        expected_check_digit = calculate_check_digit_13(main_digits_list)
    if given_check_digit == expected_check_digit:
        print('Valid ISBN Code.')
    else:
        print('Invalid ISBN Code.')
def calculate_check_digit_10(main_digits_list):
    digits_sum = 0
    for index, digit in enumerate(main_digits_list):
        digits_sum += digit * (10 - index)
        print(digits_sum)
    result = 11 - digits_sum % 11
    print(result)
    if result == 11:
        expected_check_digit = '0'
    elif result == 10:
        expected_check_digit = 'X'
    else:
        expected_check_digit = str(result)
    return expected_check_digit
    print(expected_check_digit)
def calculate_check_digit_13(main_digits_list):
    digits_sum = 0
    for index, digit in enumerate(main_digits_list):
        if index % 2 == 0:
            digits_sum += digit * 1
        else:
            digits_sum += digit * 3
    result = 10 - digits_sum % 10
    if result == 10:
        expected_check_digit = '0'
    else:
        expected_check_digit = str(result)
    return expected_check_digit
def main():
    user_input = input('Enter ISBN and length: ')
    try:
        values = user_input.split(',')
        isbn = values[0]
        length = int(values[1])
    except IndexError:
        print('Enter comma-separated values.')
        return
    except ValueError:  
        print('Length must be a number.')
        return
    try: 
        if length == 10 or length == 13:
            validate_isbn(isbn, length)
        else:
            print('Length should be 10 or 13.')
            return
    except UnboundLocalError:
        print('Length must be a number.')
        return
main()

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36

Challenge Information:

Debug an ISBN Validator - Debug an ISBN Validator

2

What did you do to investigate?

3

I printed all the steps from the validate_isbn function and even though no error occur the digits add up false. I am wondering if an error is supposed to show that I need to fix or did i accidentally mess something up in the code.

Thank you.

4

Hi @remi.sabbe.canon

Add the following print call at the bottom of the editor:

print(validate_isbn(1530051126,10))

See if you can pass test 1.

Happy coding

5

I did that. I see every variable in the function and even though it says it should return true it does not i don’t know if that is an error in the calculate_check_digits functions or a syntaxerror.

Thanks

6

in main_digits you see all digits, right? is that what it should be?
if it why even you need main_digits?