this code is written by Ahmed Magdy as an example for a simple application written using Qt/C++ framework.

hello_world.cpp

#include <QApplication>
#include <QLabel>

int main(int argc, char *argv[])
{
        QApplication a(argc, argv);                     // inirialize new instance of QtApplication
        QLabel *label = new QLabel("Hello Qt! ");       //create new label widget with initial text value "Hello Qt! "
        
        label->setMinimumSize(500,500);                 // set minimal size for the label ** the label can not be smaller than the specified minimalsize
        label->show();                                  // set the label visible as the default value of visible property is false

        return a.exec();                                // return the application execution status
}