Generate random 6-bit invitation code in PHP

Preface

In the process of system development, it is sometimes necessary to enter the invitation code when the user registers , Here is a way to quickly generate invitation codes .

    /** *  Generate invitation code  * @param unitCode */
    function create_invite_code($unitCode, $len = 3)
    {
    
        $arr = ["1", "2", "3", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"];
        $arrLen = count($arr) - 1;
        for ($i = 0; $i < $len; $i++) {
    
            $unitCode .= $arr[mt_rand(0, $arrLen)];
        }
        return $unitCode;
    }

for example ：ANC39K