main loop

[dusza]

I would not rather use timers, maybe some other solution?

[spirit]

of course your window will not be shown, because you enter in infinate loop before calling app.exec, try to rewrite code like this

QApplication a(argc, argv);
MainWindow w;
w.show();
bool res = a.exec();
while(1){}
 
return res;

QApplication a(argc, argv);
MainWindow w;
w.show();
bool res = a.exec();
while(1){}

return res;

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but, anyway, this is useless code.
take a look at QEventLoop.
btw why you can't use threads?

[wysota]

What's wrong with timers?

[dusza]

It's a bit complicated why I can't use threads but finally I figured out that I will not handle without them Timers are good but what about situation e.g. I have a function that stops program for some period of time waiting for response and with time interval set to 0 it can spoil the application I suppose, can't it?

[wysota]

Yes, but it will break it regardless if you use timers or not. Provided that you actually do something with the data you exchange with the server blocking the main thread will block your other functionality as well. Timers are the best approach in your case - threads will just make your application more complicated giving nothing in exchange.

[dusza]

Yes but in the other thread I'm just listening for data while in the main program I'm sending data to server. I think that this approach is better and easier than timers but I can be wrong.

[wysota]

Do you do anything with the data you receive?

[dusza]

No, I'm just printing it on a form. But I've tried it, I set timer interval to 0 and in trigged function I've inserted a socket recv function, which waits for data from server, but then I can't use a form because the application is suspend.

[wysota]

No, I'm just printing it on a form.

You need the main thread for that. If you block it, you won't see anything. So the argument against using timers because of a potential block is a killer also when using threads.

But I've tried it, I set timer interval to 0

What for?

and in trigged function I've inserted a socket recv function, which waits for data from server, but then I can't use a form because the application is suspend.

Use signals and slots. You don't need neither timers nor threads for accessing sockets.