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https://github.com/TheAlgorithms/Python.git
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89 lines
2.1 KiB
Python
89 lines
2.1 KiB
Python
"""
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https://en.wikipedia.org/wiki/Check_digit#Algorithms
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"""
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def get_check_digit(barcode: int) -> int:
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"""
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Returns the last digit of barcode by excluding the last digit first
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and then computing to reach the actual last digit from the remaining
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12 digits.
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>>> get_check_digit(8718452538119)
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9
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>>> get_check_digit(87184523)
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5
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>>> get_check_digit(87193425381086)
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9
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>>> [get_check_digit(x) for x in range(0, 100, 10)]
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[0, 7, 4, 1, 8, 5, 2, 9, 6, 3]
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"""
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barcode //= 10 # exclude the last digit
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checker = False
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s = 0
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# extract and check each digit
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while barcode != 0:
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mult = 1 if checker else 3
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s += mult * (barcode % 10)
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barcode //= 10
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checker = not checker
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return (10 - (s % 10)) % 10
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def is_valid(barcode: int) -> bool:
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"""
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Checks for length of barcode and last-digit
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Returns boolean value of validity of barcode
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>>> is_valid(8718452538119)
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True
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>>> is_valid(87184525)
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False
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>>> is_valid(87193425381089)
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False
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>>> is_valid(0)
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False
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>>> is_valid(dwefgiweuf)
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Traceback (most recent call last):
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...
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NameError: name 'dwefgiweuf' is not defined
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"""
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return len(str(barcode)) == 13 and get_check_digit(barcode) == barcode % 10
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def get_barcode(barcode: str) -> int:
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"""
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Returns the barcode as an integer
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>>> get_barcode("8718452538119")
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8718452538119
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>>> get_barcode("dwefgiweuf")
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Traceback (most recent call last):
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...
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ValueError: Barcode 'dwefgiweuf' has alphabetic characters.
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"""
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if str(barcode).isalpha():
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raise ValueError(f"Barcode '{barcode}' has alphabetic characters.")
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elif int(barcode) < 0:
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raise ValueError("The entered barcode has a negative value. Try again.")
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else:
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return int(barcode)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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"""
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Enter a barcode.
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"""
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barcode = get_barcode(input("Barcode: ").strip())
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if is_valid(barcode):
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print(f"'{barcode}' is a valid barcode.")
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else:
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print(f"'{barcode}' is NOT a valid barcode.")
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