Hello World Qt, hand made from Empty qmake Project

This video show how to create Empty qmake Project in Qt Creator, create .cpp and edit .pro to make a Hello World application.


main.cpp

#include <QApplication>
#include <QPushButton>

int main(int argc, char *argv[]){
    QApplication app(argc, argv);
    QPushButton qPushButton("Hello Qt");
    qPushButton.show();
    return app.exec();
}

You will be reported with error of:
QApplication: No such file or directory
QPushButton: No such file or directory

To fix it: Edit HelloQt.pro to add the code QT+=widgets.

QT+=widgets
SOURCES += \
    main.cpp