42 lines
1.1 KiB
Python
42 lines
1.1 KiB
Python
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#!/usr/bin/env python
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# Luhn Algorithm Example - Developed by acidvegas in Python (https://git.acid.vegas/msr90)
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def modulus10(card_number: str) -> str:
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'''
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Validate a card number using the Luhn Algorithm
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:param card_number: The card number to validate
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'''
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digits = [int(d) for d in card_number]
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total_sum = 0
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reversed_digits = digits[::-1]
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for i in range(len(reversed_digits)):
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digit = reversed_digits[i]
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if i % 2 != 0:
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digit = digit * 2
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if digit > 9:
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digit -= 9
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total_sum += digit
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check_digit = (10 - (total_sum % 10)) % 10
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full_card_number = card_number + str(check_digit)
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if (total_sum + check_digit) % 10 != 0:
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raise ValueError('failed luhn check (non-divisible by 10)')
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return full_card_number
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if __name__ == '__main__':
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card_number = input('Enter your card number without the last digit:')
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if not card_number.isdigit():
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raise ValueError('invalid card number')
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print(f'Full card number: {modulus10(card_number)}')
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