操作二位数组增删改

1.向二维数组中值，修改、删除、或添加值；（方式一：引用方式）

    public function test5()
    {
        echo "<pre>";
        $twoarr = [
            ["id"=>"1","name"=>"赵锐庆","age"=>"12"],
            ["id"=>"2","name"=>"赵园庆","age"=>"12"],
            ["id"=>"3","name"=>"刘亦菲","age"=>"12"],
            ["id"=>"4","name"=>"奥特曼","age"=>"12"],
        ];
        #向二维数组中每个成员添加一个班级列class与学校列school 并删除年龄的字段
        foreach($twoarr as &$val){#注意引用是加载$val上的
            $val["class"] = "大班";
            $val["school"] = "哈佛大学";
            unset($val["age"]);
        }
        print_r($twoarr);

    }