qt一个按钮实现打开和关闭新窗口

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include 
#include
class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
    QWidget *w1;
    QPushButton *but1;
    bool flag = true;
    void ctrol();
    
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include
#include 
#include
Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    but1 = new QPushButton;
    but1->setParent(this);
    but1->setText("open");
    resize(700,700);
    but1->move(300,300);
    but1->resize(100,60);
    connect(but1,&QPushButton::clicked,this,&Widget::ctrol);//类似循环，点击一次，运行一次
}

void Widget::ctrol()
{
    if(flag==true)
    {
        w1=new QWidget;//w1定义在widegt.h中
        w1->setWindowTitle("Second");
        w1->resize(700,200);
        w1->show();
        flag=false;
        but1->setText("close");
        qDebug()<<"open yes";
    }
    else
    {
        w1->close();
        flag=true;
        but1->setText("open");
        qDebug()<<"close yes";
    }
}

Widget::~Widget()
{
}