Qt closes the child window when the main window is closed

1, this specifies the main window as the parent class

void MainWindow::on_pushButton_clicked()
{
    
    
    Dialog *aa = new Dialog(this);
    aa->show();
}

2. Rewrite the main window closeEvent event
mainwindow.h

QVector<Dialog*> m_test;

mainwindow.cpp

QVector<Dialog*> m_test;

void MainWindow::closeEvent(QCloseEvent *event)
{
    
    
    qDebug() << "close";
    foreach(Dialog *cc, m_test)
    {
    
    
        if(cc != nullptr)
        {
    
    
            delete cc;
            cc = nullptr;
        }
    }
}

void MainWindow::on_pushButton_clicked()
{
    
    
    Dialog *aa = new Dialog();
    m_test.append(aa);
    aa->show();
}

When the child window is closed, the child window object is deleted at the same time, and the resource can be released using the Qt::WA_DeleteOnClose property

void MainWindow::on_pushButton_clicked()
{
    
    
    Dialog *aa = new Dialog();
    aa->setAttribute(Qt::WA_DeleteOnClose, true);
    aa->show();
}