Qt窗口关闭弹出确认对话框

1、在mainwindow中重写closeEvent

void closeEvent(QCloseEvent *event);

2、在cpp中实现

QDialog* log = new QDialog(this);
    log->setObjectName("log");
    log->setStyleSheet("#log{background:#3379B7;}");
    log->deleteLater();
    log->setWindowTitle("退出平台");
    QRect clientRect = QApplication::desktop()->availableGeometry();
    log->setGeometry(clientRect.width()/2,clientRect.height()/2,200,100);
    QLabel* lel = new QLabel(log);
    lel->setText("确定退出平台吗?");
    lel->setStyleSheet("QLabel{font-family:'宋体';font-size:20px;color:white;}");
    lel->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
    QPushButton* okBtn = new QPushButton(log);
    QPushButton* clsBtn = new QPushButton(log);
    okBtn->setText("确定");
    clsBtn->setText("取消");
    okBtn->setMaximumWidth(100);
    clsBtn->setMaximumWidth(100);

    QObject::connect(okBtn,&QPushButton::clicked,[=]()
    {
        log->done(RET_OK);
    });
    QObject::connect(clsBtn,&QPushButton::clicked,[=]()
    {
        log->done(RET_ERR);
    });
    QHBoxLayout* hLayout = new QHBoxLayout();
    hLayout->setSpacing(5);
    hLayout->addStretch();
    hLayout->addWidget(okBtn);
    hLayout->addWidget(clsBtn);
    QVBoxLayout* v = new QVBoxLayout();
    v->addWidget(lel);
    v->addItem(hLayout);
    log->setLayout(v);
    if(RET_OK==log->exec())
    {
        event->accept();
    }
    else
    {
       event->ignore();
    }

3、关闭窗口或者主动调用this->close()函数就会触发closeEvent