Open console with GUI only if Qapp is called with true argument.

[filipdns]

Hello,

I nned help because I want to have my QApplication is opened with a console only when I'm calling it with for example :

C:/app.exe true

The goal is to have only one exe but with argument true, the console can be open to show qdebug messages, and not with arguments false.

I know how to have the console on with includung CONFIG+= console inside pro file, but how to disable it with argument false?

Thank you for your help

Philippe

[JonB]

@filipdns
This has been asked before. A Windows executable is either a console application or a UI application: this is determined at link time (and I imagine it's what CONFIG+= console affects). You cannot alter this at runtime for the same executable.

[filipdns]

hello,

I found the solution using FreeConsole();

best regards

Philippe

[JonB]

@filipdns
Then presumably you do not use CONFIG+= console? Or you do still use that if you use the Windows SDK FreeConsole()? I can only think you are build a Windows UI app and switching on/off the display of a console, but not just building a console app?

Doesn't the console flash up and show, before you hide it? This is discussed in, say, https://stackoverflow.com/questions/66185000/how-can-i-do-the-freeconsole-but-faster-on-c, and elsewhere.

[filipdns]

In pro file I add CONFIG+= console and when I don't want to have the console appear, then I pass my argument to false, example C:/app.exe false

and inside my app I add:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    bool debug=false;

    debug=QString(argv[1])=="false"?false:true;

    if(!debug){
        FreeConsole();

    }
...

[JonB]

@filipdns
Great, so at least I understand. You have a UI application (QApplication) and you have CONFIG+= console. I didn't know that was allowed. I guess that makes a Windows UI application also create and show a separate window which is a console? Maybe (I don't know) the same could be achieved without CONFIG+= console and instead having if (debug) AllocConsole().

BTW, have you ensured your code works both ways if run outside Qt Creator?

[SimonSchroeder]

I am with @JonB. A console app on Windows cannot have an event loop and widgets. And a GUI application does not show its console by default. @filipdns have you tried to show a window with your current approach? I doubt that it works. From my understanding CONFIG needs to be without console to have GUI application on Windows (just as @JonB said). Then you need to use AllocConsole() to create a console instead of using FreeConsole(). An additional benefit is that there will be no flickering of the console when it is not enabled. This should be the proper way.

[mchinand]

How does QtCreator's 'Run in terminal' option work to open a Windows console when starting an application within QtCreator?

[JonB]

@mchinand
Well, the point is that Creator is doing that opening, and attaching the outputs as necessary. It does not change your application to do so. Which is why I suggested the OP test whether what works presently works outside Creator. Creator is doing something like AllocConsole() (Windows) to create that terminal and attach it.

[filipdns]

@SimonSchroeder Thank you for your suggestion but with -=console in pro file and Alloconsole(), I have terminal openning yes but no qDebug or console.log information display on it.

The +=console method with Freeconsole() work fine for me even I have a very short time a console appearing when I'm starting my application when I don't want a console.

[JonB]

@filipdns said in Open console with GUI only if Qapp is called with true argument.:

Alloconsole(), I have terminal openning yes but no qDebug or console.log information display on i

You would presumably have to do stuff to redirect stdout/err etc. to the allocated console.

[SimonSchroeder]

@JonB said in Open console with GUI only if Qapp is called with true argument.:

You would presumably have to do stuff to redirect stdout/err etc. to the allocated console.

You certainly have to: https://stackoverflow.com/a/57241985/6954968