How to simulate mouse event with Qt?

I want to simulation mouse event with Qt. For example, when I press one key on the keyboard, the program can simulate a mouse click event. I have tried the code below, but when I press 'K', the program stops and gives me an error:

The program has unexpectedly finished.

    case Qt::Key_K:
        QMouseEvent *mEvnPress;
        QMouseEvent *mEvnRelease;
        mEvnPress = new QMouseEvent(QEvent::MouseButtonPress, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
        mEvnRelease = new QMouseEvent(QEvent::MouseButtonRelease, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
        QCoreApplication::sendEvent(QWidget::focusWidget(),mEvnPress);
        QCoreApplication::sendEvent(QWidget::focusWidget(),mEvnRelease);
        break;