Using qtgui for plotting constellations

GNU Radio
1

hello everybody,

I wanted to use constellation plot of gnuradio in my top block in c++. I
actually use qtcreator in ubuntu and gnuradio 3.7.3. After I found out
that I must add “-lgnuradio-qtgui” to the .pro file of qtcreator for
using qtgui of gnuradio, I ran the program but it didn’t open any GUI!!!

my code is like this :

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#include <gnuradio/qtgui/const_sink_c.h>

#include <QtGui/QApplication>
#include <qapplication.h>
#include

using namespace gr;

int main()
{
// some blocks here …

 qtgui::const_sink_c::sptr constellation =

qtgui::const_sink_c::make(10, “constellation”, 1, NULL);

  // some connections ....

  tb->run();

  return 0;

}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

What is the problem!? Why I can’t see any GUI?

best