Credit Card Validator

This is a simple python script that validates credit card numbers using the Luhn algorithm. The Luhn algorithm is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, National Provider Identifier numbers in the United States, and Canadian Social Insurance Numbers.

Below is the project.

# Credit Card Validator Program
card_number = input("Enter a card number ")# Enter a card number
card_number = card_number.replace(" ","")# Remove spaces in number
card_number = card_number.replace("-","")# Remove underscores in number
card_number = card_number[::-1]# Reverse the number

# Create variables
sum_of_odd_nums = 0
sum_of_even_nums = 0
total = 0

# Loop through and sum all odd placed numbers
for i in card_number[::2]:
    sum_of_odd_nums += int(i)

# Lopp through and double all even placed numbers
for i in card_number[1::2]:
    x = int(i) * 2
    # If x is greater than 9, split it and add them all up
    if x >= 10:
        sum_of_even_nums += (1 + (int(x) % 10))
    # Else it is below 10, sum all up
    else:
        sum_of_even_nums += int(x)

# Total all summed even and summed odd variables
total = sum_of_even_nums + sum_of_odd_nums

# If total is divisible by 10, then valid
if total % 10 == 0:
    print("Valid")
# Else, it is invalid
else:
    print("Invalid")