Credit Card Validator

Open in Visual Studio Code

This program validates your credit card number using luhn algorithm. It can also display the company of the credit card you are using.

What is Luhn Algorithm?

Most cards use an algorithm invented by Hans Peter Luhn of IBM. According to Luhn’s algorithm, you can determine if a credit card number is (syntactically) valid as follows:

  • Multiply every other digit by 2, starting with the number’s second-to-last digit, and then add those products’ digits together.
  • Add the sum to the sum of the digits that weren’t multiplied by 2.
  • If the total’s last digit is 0 (or, put more formally, if the total modulo 10 is congruent to 0), the number is valid!


gcc validator.cpp -o validator


Input: 4003600000000014
Output: Visa
Input: 374245455400126
Output: Amex
Input: 60115564485789458
Output: INVALID! Please enter the valid number.

You can specify the number of cards you want to validate by changing the MAX macro in the code.

by default MAX = 1


  • Add file handling support


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