show a pop up or message box in my console application

[spirit]

It's odd situation of using console based app with ui. Why do you need such behavior?

[yeye_olive]

Why do you keep calling "console application" an application that displays message boxes and forms designed in QtDesigner? It is a GUI application, and you must instantiate QApplication. This does not prevent you from reading from the standard input and writing to the standard output like console applications do.

All you have to do is instantiate the widgets, show them when you feel like it, and make sure an event loop runs for the user to interact with them. You can use std::cin and std::cout as much as you want.