代码如下图：这样子在foreach中是无法修改class_history的。正确的应该是去掉??[]判断。

    public function actionY()
    {
        $array = [
            'name'=>'aaa',
            'class_history'=>[
                [
                    'class_name'=>'一班',
                    'class_num'=>1
                ],
                [
                    'class_name'=>'二班',
                    'class_num'=>2
                ]
            ]
        ];
        foreach ($array['class_history']??[] as &$item) {
            $item['class_name'] = '三班';
            $item['class_num'] = 3;
        }
        var_dump($array);
    }