Debug an ISBN Validator - Debug an ISBN Validator

Tell us what’s happening:

have to checj isbn number contains non number ? how to check ? this

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: ')
    if ','not in user_input:
        print('Enter comma-separated values.')
        return
    values = user_input.split(',')
    try:
        isbn = values[0]
        length = int(values[1])
    except ValueError:
        print('Length must be a number.')
        return

        if length == 10 or length == 13:
            validate_isbn(isbn, length)
            return
        else:
            print('Length should be 10 or 13.')
            return
    

#main()

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Challenge Information:

Debug an ISBN Validator - Debug an ISBN Validator

Hi there,

Sorry it’s taken us so long to respond.

A couple of ways to do this come to mind, but I’m sure there are other valid approaches:

  • You could use a regular expression.
  • You could loop over each character in isbn and use !isbn.includes()

Just make sure you strip off the last check character first if length is 10 since those isbn values can end in “X”.

Happy coding!

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