qt-creator/share/qtcreator/templates/mobileapp/main.cpp

#include "mainwindow.h"

#include <QtGui/QApplication>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    MainWindow mainWindow;
    mainWindow.setOrientation(MainWindow::ScreenOrientationAuto); // ORIENTATION
    mainWindow.showExpanded();

    return app.exec();
}