qt设置父窗体关闭后同时关闭子窗体

首先重写closeEvent:
并加入这一行代码即可​​​this->setAttribute(Qt::WA_DeleteOnClose);​​

void MainWindow::closeEvent(QCloseEvent *event)
{
    //关闭时释放内存
    this->setAttribute(Qt::WA_DeleteOnClose);
    WriteSettings();
    QMainWindow::closeEvent(event);
}