PHP递归

/*
 * 递归获取所有分类
 * @param int $parent_id
 * @param int $lv
 * @param array $res
 * @return arary
 */
public function get_all_type($parent_id=0,&$lv=0,&$res=array()){
    $where['parent_id']=$parent_id;
    $list=$this->where($where)->select();
    if(!empty($list[0])){
        $lv++;
        foreach($list as $item){
            $item['lv']=$lv;
            $nbsp='';
            for($i=1;$i<$lv;$i++){
                $nbsp.='&nbsp;&nbsp;&nbsp;&nbsp;';
            }
            $item['lv_str']=$nbsp;
            $res[$item['type_id']]=$item;
            $this->get_all_type($item['type_id'],$lv,$res);
        }
        $lv--;
    }
    return $res;
}

/**
 * 递归获取用户所有下线
 * @param int $parent_id
 * @param array $res
 * @return array
 */
function get_user_all_childs($parent_id = 0, &$res = array()) {
    $list = $db->getAll("SELECT user_id FROM users WHERE parent_id = '$parent_id'");
    if (!empty($list[0])) {
        foreach ($list as $item) {
            $res[] = $item['user_id'];
            get_user_all_childs($item['user_id'], $res);
        }
    }
    return $res;
}