QMessageBox 的使用 官方帮助文档的例子

//内容显示
    QMessageBox msgBox;
    msgBox.setText("The document has been modified.");
    msgBox.exec();

    //选择信息框
    QMessageBox msgBox2;
    msgBox2.setText("The document has been modified.");
    msgBox2.setInformativeText("Do you want to save your changes?");
    msgBox2.setStandardButtons(QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel);
    msgBox2.setDefaultButton(QMessageBox::Save);
    int ret = msgBox2.exec();

    switch (ret)
    {
    case QMessageBox::Save:
        // Save was clicked
        break;
    case QMessageBox::Discard:
        // Don't Save was clicked
        break;
    case QMessageBox::Cancel:
        // Cancel was clicked
        break;
    default:
        // should never be reached
        break;
    }

    //警告框
    int ret3 = QMessageBox::warning(this, tr("My Application"),
                                    tr("The document has been modified.\n"
                                       "Do you want to save your changes?"),
                                    QMessageBox::Save | QMessageBox::Discard
                                    | QMessageBox::Cancel,
                                    QMessageBox::Save);