Amazing-Python-Scripts

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# Checking entered number is a isbn number or not
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def valid_ISBN(isbn):
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    # Remove hyphens and spaces from the ISBN
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    isbn = isbn.replace('-', '').replace(' ', '')
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    # Check if the length of the ISBN is valid
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    if len(isbn) == 10:
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        return valid_ISBN10(isbn)
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    elif len(isbn) == 13:
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        return valid_ISBN13(isbn)
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    else:
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        return False
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# Checking the entered number is a valid 10-digit isbn number
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def valid_ISBN10(isbn):
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    # Check if the ISBN is valid according to the ISBN-10 algorithm
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    if not isbn[:-1].isdigit() or not isbn[-1] in ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'X']:
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        return False
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    # Calculate the check digit
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    checkDigit = 0
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    weight = 10
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    for digit in isbn[:-1]:
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        checkDigit += int(digit) * weight
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        weight -= 1
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    checkDigit %= 11
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    if isbn[-1] == 'X':
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        checkDigit = 'X'
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    # Validate the check digit
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    return str(checkDigit) == isbn[-1]
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# Checking the entered number is a valid 13-digit isbn number
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def valid_ISBN13(isbn):
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    # Check if the ISBN is valid according to the ISBN-13 algorithm
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    if not isbn.isdigit():
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        return False
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    # Calculate the check digit
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    checkDigit = 0
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    weight = [1, 3] * 6
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    for digit, w in zip(isbn[:-1], weight):
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        checkDigit += int(digit) * w
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    checkDigit %= 10
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    checkDigit = (10 - checkDigit) % 10
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    # Validate the check digit
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    return str(checkDigit) == isbn[-1]
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# Ask the user to enter an ISBN number
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isbnNumber = input("\nEnter an ISBN number: ")
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# Validate the ISBN number
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if valid_ISBN(isbnNumber):
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    print("\nValid ISBN number.\n")
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else:
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    print("\nInvalid ISBN number.\n")
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