function add_user($username, $password, $email, $uid = 0, $questionid = '', $answer = '', $regip = '') {
        $regip = empty($regip) ? $this->base->onlineip : $regip;
        $salt = substr(uniqid(rand()), -6);
        $password = md5(md5($password).$salt);
        $sqladd = $uid ? "uid='".intval($uid)."'," : '';
        $sqladd .= $questionid > 0 ? " secques='".$this->quescrypt($questionid, $answer)."'," : " secques='',";
        $this->db->query("INSERT INTO ".UC_DBTABLEPRE."members SET $sqladd username='$username', password='$password', email='$email', regip='$regip', regdate='".$this->base->time."', salt='$salt'");
        $uid = $this->db->insert_id();
        $this->db->query("INSERT INTO ".UC_DBTABLEPRE."memberfields SET uid='$uid'");
        /**ucenter首次登录激活**/
        $this->db->query("INSERT INTO ".DISCUZ_DBTABLEPRE."common_member SET uid='$uid', username='$username', password='$password', email='$email', adminid='0', groupid='10', regdate='".$this->base->time."', credits='0', timeoffset='9999'");
        $this->db->query("INSERT INTO ".DISCUZ_DBTABLEPRE."common_member_status SET uid='$uid', regip='$regip', lastip='$regip', lastvisit='".$this->base->time."', lastactivity='".$this->base->time."', lastpost='0', lastsendmail='0'");
        $this->db->query("INSERT INTO ".DISCUZ_DBTABLEPRE."common_member_profile SET uid='$uid'");
        $this->db->query("INSERT INTO ".DISCUZ_DBTABLEPRE."common_member_field_forum SET uid='$uid'");
        $this->db->query("INSERT INTO ".DISCUZ_DBTABLEPRE."common_member_field_home SET uid='$uid'");
        $this->db->query("INSERT INTO ".DISCUZ_DBTABLEPRE."common_member_count SET uid='$uid', extcredits1='0', extcredits2='0', extcredits3='0', extcredits4='0', extcredits5='0', extcredits6='0', extcredits7='0', extcredits8='0'");
        /**ucenter首次登录激活over**/
        return $uid;
    }

define('DISCUZ_DBTABLEPRE', 'pre_');