WBW\Library\Core\Algorithm\Checksum\LuhnAlgorithm::check()

Complexity

Conditions	4
Paths	5

Size

Total Lines	31
Code Lines	13

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

<?php
    public static function check($str) {

        // Initialize.
        $sum    = 0;
        $length = strlen($str);
        $parity = $length % 2;

        // Get the sum.
        $sum += substr($str, $length - 1);

        // Handle each character.
        for ($i = $length - 2; 0 <= $i; --$i) {

            // Get the digit.
            $digit = intval(substr($str, $i, 1));

            // Check the parity.
            if ($parity === $i % 2) {
                $digit *= 2;
            }
            if (9 < $digit) {
                $digit -= 9;
            }

            // Add the digit.
            $sum += $digit;
        }

        // Return.
        return 0 === $sum % 10;
    }