有个小问题呀！关于这个类之前的头文件的，求解答

```c++
#include "widget.h"
#include "ui_widget.h"
#include "QListWidget"
#include "QWidget"
#include "QStackedLayout"

Widget::Widget(QWidget *parent) :
![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/290091436636151.png "#left")

    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);

    QListWidget *listWidget = new QListWidget();
    listWidget->addItem("One");
    listWidget->addItem("Two");
    listWidget->addItem("Three");

    QWidget *widget1 = new Qwidget();
    QWidget *widget2 = new Qwidget();
    QWidget *widget3 = new Qwidget();

    QLabel *label1 = new Qlabel("LABEL ONE", widget1);
    QLabel *label2 = new Qlabel("LABEL TWO", widget2);
    QLabel *label3 = new Qlabel("LABEL THREE", widget3);

    QStackedLayout *sLayout = new QStackedLayout();
    sLayout->addWidget(widget1);
    sLayout->addWidget(widget2);
    sLayout->addWidget(sLayout);

    QHBoxLayout *hLayout = new QHBoxLayout();
    hLayout->addWidget(listWidget);
    hLayout->addLayout(sLayout);

    setLayout(hLayout);

    QObject::connect(listWidget, &QListWidget::currentRowChanged, sLayout, &QStackedLayout::setCurrentIndex);
}


Widget::~Widget()
{
    delete ui;
}

![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/051691436636155.png "#left")