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