code: public static function passwdGen($length = 8, $flag = 'ALPHANUMERIC')
      {
          switch ($flag) {
              case 'NUMERIC':
                  $str = '0123456789';
                  break;
              case 'ALPHA':
                  $str = 'abcdefghijkmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
                  break;
              case 'ALPHA_LOWER':
                  $str = 'abcdefghijkmnopqrstuvwxyz';
                  break;
              default:
                  $str = 'abcdefghijkmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
                  break;
          }
  
          for ($i = 0, $passwd = ''; $i < $length; $i++) {
              $passwd .= substr($str, mt_rand(0, \strlen($str) - 1), 1);
          }
  
          return $passwd;
      }
docs: Random password generator
  
  @param integer $length Desired length (optional)
  @param string $flag Output type (NUMERIC, ALPHANUMERIC, ALPHA, ALPHA_LOWER)
  
  @return string Password