Credit Card Validator

Overview

This is a simple C++ program that uses the Luhn Algorithm to validate credit card numbers. The program prompts the user to input a credit card number and then determines whether it's a valid credit card number or not.

Luhn Algorithm

The Luhn Algorithm, also known as the "modulus 10" or "mod 10" algorithm, is a simple checksum formula used to validate a variety of identification numbers, especially credit card numbers.

The algorithm works as follows:

1. Starting from the rightmost digit (the check digit) and moving left, double the value of every second digit.
2. If doubling a digit results in a two-digit number, add the digits of that number together.
3. Sum all the digits, including the ones that were not doubled.
4. If the total sum is a multiple of 10, the credit card number is valid; otherwise, it's invalid.

Usage

1. Clone this repository to your local machine.

   git clone https://github.com/swetamishra123/Credit-Card-Validator.git

2. Compile the C++ program using a C++ compiler.

   g++ main.cpp -o main

3. Run the program:

   ./main

4. Follow the on-screen instructions to enter credit card numbers for validation. You can exit the program by typing 'exit'.

Example Output

This program uses the Luhn Algorithm to validate a CC number.
You can enter 'exit' anytime to quit.
Please enter a CC number to validate: 4263982640269299
Valid!
Please enter a CC number to validate: 4983948596068655
Invalid!
Please enter a CC number to validate: 8957859403857785
Invalid!
Please enter a CC number to validate: 2223000048410010
Valid!
Please enter a CC number to validate: exit

Program Explanation

• The program starts by prompting the user to enter a credit card number. You can exit by typing 'exit'.
• It checks if the input is a valid number (only digits), and if not, it asks for input again.
• It then applies the Luhn Algorithm to validate the credit card number.
• The result is displayed as "Valid!" if the credit card is valid and "Invalid!" if it's not.

This program demonstrates a simple implementation of the Luhn Algorithm for credit card validation in C++.

License

This project is open-source and available under the MIT License.