PHP Function to Validate EANs

ean_check.php

<?php

    /*
        0346745008178
        Should fail - checksum should be 9

        5060096384137
        Should pass

        5020650002112
        Should pass
    */

    $eans = array(
        '5020650002112',
        '5060096384137',
        '0346745008178'
    );

    foreach ($eans as $ean) {
        var_dump(ean_check($ean));
    }

    function ean_check($ean) {
        $ean = strrev($ean);
        // Split number into checksum and number
        $checksum = substr($ean, 0, 1);
        $number = substr($ean, 1);
        $total = 0;
        for ($i = 0, $max = strlen($number); $i < $max; $i++) {
            if (($i % 2) == 0) {
                $total += ($number[$i] * 3);
            } else {
                $total += $number[$i];
            }
        }
        $mod = ($total % 10);
        $calculated_checksum = (10 - $mod);
        if ($calculated_checksum == $checksum) {
            return true;
        } else {
            return false;
        }
    }