Luhn Algorithm Validator

Overview

This project is a simple Luhn Algorithm Validator implemented in Python. The Luhn algorithm, also known as the modulus 10 algorithm, is a widely used checksum formula to validate credit card numbers and other identification numbers.

This project was developed as part of the 'Scientific Computing with Python' certification on freeCodeCamp, where I learned string manipulation techniques and applied them to implement this algorithm.

Features

• Implements the Luhn Algorithm to verify card numbers.
• Handles input with hyphens (-) or spaces ( ) by removing them before processing.
• Uses string manipulation techniques, including str.maketrans() and .translate().
• Works with any card number input as a string.
• Provides clear output indicating whether the card number is valid or not.

How It Works

1. The input card number is cleaned by removing - and spaces.
2. The number is processed using the Luhn Algorithm, where:
   • Digits in odd positions (from the right) are summed directly.
   • Digits in even positions are doubled, and if the result is greater than 9, the digits of the product are summed.
   • The total sum is calculated, and if it is divisible by 10, the card number is valid.
3. The program prints VALID! or INVALID! based on the result.

Code Example

card_number = '4111-1111-4555-1142'  # Example input

Sample Output

VALID!