Luhn Algorithm

This is a zero dependency implementation of the Luhn Algorithm for PHP 7.4 and above. The Luhn Algorithm is used to validate things like credit cards and national identification numbers. More information on the algorithm can be found at Wikipedia.

Installation

Install with Composer:

composer require nekman/luhn-algorithm

Usage

In order to instantiate a new instance of the library, use the factory:

use Nekman\LuhnAlgorithm\LuhnAlgorithmFactory;

$luhn = LuhnAlgorithmFactory::create();

You can find the library facade in the LuhnAlgorithmInterface.php file.

The Number class is a container class that holds the actual number and the check digit. It does no validation nor does it calculate the check digit. It exists to clearly separate the number from the check digit and to define when the check digit exists or not. To simplify the process of validating a number you can use the named constructor Number::fromString() like this:

use Nekman\LuhnAlgorithm\Number;

// Assume $creditCard is from a form.
$number = Number::fromString($creditCard);

if ($luhn->isValid($number)) {
    // Number is valid.
}

Alternatively, if you want to calculate the checksum or check digit for a number:

use Nekman\LuhnAlgorithm\Number;

$number = new Number(12345);

$checksum = $luhn->calcChecksum($number);

$checkDigit = $luhn->calcCheckDigit($number);

Versioning

This project complies with Semantic Versioning.

Changelog

For a complete list of changes, and how to migrate between major versions, see releases page.