Detaillierte Erklärung des rekursiven PHP-Algorithmus

//曾经的数据库查询获取方式$res = $this->db->query("select * from menu where pid = 0");foreach($res as 
$k=>$v){     $res[$k]['child'] = $this->db->query("select * from menu where pid =".$v['id']);
}

  public function getMenus(){
    //查询
    $res = $this->db->get('menu')->result_array();    $res = $this->getChild($res);
    print_r($res)；
}/**
 * 递归 树节点算法
 * @param array $array
 * @param number $pid
 */private function getChild($array,$pid = 0){
    $data = array();    foreach ($array as $k=>$v){        //PID符合条件的
        if($v['pid'] == $pid){            //寻找子集
            $child = $this->getChild($array,$v['id']);            //加入数组
            $v['child'] = $child?:array(); 
            $data[] = $v;//加入数组中
        }
    }    return $data;
}

Array(

[0] => Array

    (

        [id] => 1
        [title] => PHP中文网
        [pid] => 0
        [sort] => 0
        [child] => Array
            (
            )

)
[1] => Array
    (
        [id] => 2
        [title] => 系统设置
        [pid] => 0
        [sort] => 99
        [child] => Array
            (
                [0] => Array
                    (
                        [id] => 4
                        [title] => 权限管理
                        [pid] => 2
                        [sort] => 2
                        [child] => Array
                            (
                            )

                    )

                [1] => Array
                    (
                        [id] => 5
                        [title] => 菜单栏目
                        [pid] => 2
                        [sort] => 0
                        [child] => Array
                            (
                            )

                    )

                [2] => Array
                    (
                        [id] => 3
                        [title] => 管理员
                        [pid] => 2
                        [sort] => 99
                        [child] => Array
                            (
                            )

                    )

            )

    )
)