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credit_card_validator.py
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credit_card_validator.py
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"""
Python script to check validity of credit card numbers
Author : PythonCircle.Com
Read more : https://www.pythoncircle.com/post/485/python-script-8-validating-credit-card-number-luhns-algorithm/
"""
import sys
def usage():
msg = """
usage:
python3 credit_card_validator credit_card_number
example:
python3 credit_card_validator 34678253793
"""
print(msg)
def get_cc_number():
if len(sys.argv) < 2:
usage()
sys.exit(1)
return sys.argv[1]
def sum_digits(digit):
if digit < 10:
return digit
else:
sum = (digit % 10) + (digit // 10)
return sum
def validate(cc_num):
# reverse the credit card number
cc_num = cc_num[::-1]
# convert to integer list
cc_num = [int(x) for x in cc_num]
# double every second digit
doubled_second_digit_list = list()
digits = list(enumerate(cc_num, start=1))
for index, digit in digits:
if index % 2 == 0:
doubled_second_digit_list.append(digit * 2)
else:
doubled_second_digit_list.append(digit)
# add the digits if any number is more than 9
doubled_second_digit_list = [sum_digits(x) for x in doubled_second_digit_list]
# sum all digits
sum_of_digits = sum(doubled_second_digit_list)
# return True or False
return sum_of_digits % 10 == 0
if __name__ == "__main__":
print(validate(get_cc_number()))