Debug an ISBN Validator - Debug an ISBN Validator

Python
1

Tell us what’s happening:

I need help with steps 9,10,11, 18,19,20 please. I don’t know how to debug this further. I am not sure exactly in which function I should make the changes.

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]
    given_check_digit = isbn[length]
    main_digits_list = [int(digit) for digit in main_digits]
    # Calculate the check digit from other digits
    if length == 10:
        expected_check_digit = calculate_check_digit_10(main_digits_list)
    else:
        expected_check_digit = calculate_check_digit_13(main_digits_list)
    # Check if the given check digit matches with the calculated check digit
    if given_check_digit == expected_check_digit:
        print('Valid ISBN Code.')
    else:
        print('Invalid ISBN Code.')
def calculate_check_digit_10(main_digits_list):
    # Note: You don't have to fully understand the logic in this function.
    digits_sum = 0
    # Multiply each of the first 9 digits by its corresponding weight (10 to 2) and sum up the results
    for index, digit in enumerate(main_digits_list):
        digits_sum += digit * (10 - index)
    # Find the remainder of dividing the sum by 11, then subtract it from 11
    result = 11 - digits_sum % 11
    # The calculation result can range from 1 to 11.
    # If the result is 11, use 0.
    # If the result is 10, use upper case X.
    # Use the value as it is for other numbers.
    if result == 11:
        expected_check_digit = '0'
    elif result == 10:
        expected_check_digit = 'X'
    else:
        expected_check_digit = str(result)
    return expected_check_digit
def calculate_check_digit_13(main_digits_list):
    # Note: You don't have to fully understand the logic in this function.
    digits_sum = 0
    # Multiply each of the first 12 digits by 1 and 3 alternately (starting with 1), and sum up the results
    for index, digit in enumerate(main_digits_list):
        if index % 2 == 0:
            digits_sum += digit * 1
        else:
            digits_sum += digit * 3
    # Find the remainder of dividing the sum by 10, then subtract it from 10
    result = 10 - digits_sum % 10
    # The calculation result can range from 1 to 10.
    # If the result is 10, use 0.
    # Use the value as it is for other numbers.
    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: ')
    values = user_input.split(',')
    try:
        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:
        isbnTemp = int(isbn)
    except ValueError:
        print('Invalid character was found.')
    if length == 10 or length == 13:
        validate_isbn(isbn, length)
    else:
        print('Length should be 10 or 13.')

# main()

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Challenge Information:

Debug an ISBN Validator - Debug an ISBN Validator

2

Here are some troubleshooting steps you can follow. Focus on one test at a time:

Are there any errors or messages in the console?
What is the requirement of the first failing test?
Check the related User Story and ensure it’s followed precisely.
What line of code implements this?
What is the result of the code and does it match the requirement? (Write the value of a variable to the console at that point in the code if needed.)

If this does not help you solve the problem, please reply with answers to these questions.

3

These are the errors currently in the console:

// running tests
9. When the user enters 1530051126,10, you should see the message Valid ISBN Code. in the console.
10. When the user enters 9781530051120,13, you should see the message Valid ISBN Code..
11. When the user enters 1530051125,10, you should see the message Invalid ISBN Code..
18. When the user enters 9971502100,10, you should see the message Valid ISBN Code..
19. When the user enters 080442957X,10, you should see the message Valid ISBN Code..
20. When the user enters 9781947172104,13, you should see the message Valid ISBN Code..
// tests completed

The requirement of the first failing test is that When the user enters 1530051126,10, they should see the message Valid ISBN Code.

What line of code implements this? >> I think that’s what my weak point is, I don’t know which one exactly I need to modify. There is the validation function, but I don’t know what to change in it?

4

What if the ISBN ends with an X?

try:
    # some code
except Exception as e:
    print(f"An error occurred: {e}")

Try putting this inside validate_isbn to see if there are errors. This should catch all errors.

5

I realized what was wrong with the code. Thanks for your help!