<![CDATA[Checking if running as command-line (QCoreApplication) or GUI]]>Is it correct to write:

if (qApp)
{
     // Do gui stuff
}
else
{
    // Do command line stuff
}

Thanks, David

]]>https://forum.qt.io/topic/165244/checking-if-running-as-command-line-qcoreapplication-or-guiRSS for NodeSat, 07 Nov 2026 01:45:11 GMTFri, 06 Nov 2026 11:01:50 GMT60<![CDATA[Reply to Checking if running as command-line (QCoreApplication) or GUI on Fri, 06 Nov 2026 19:05:19 GMT]]>@Perdrix said in Checking if running as command-line (QCoreApplication) or GUI:

@JonB I build a GUI application which instantiates a QApplication in its main(), and a completely different piece of code is used for the command line application which creates a QCoreApplication.

So I think that qApp will work in that case?

Hi,

Something is not clear: are you starting both the CLI and the GUI from the same main function ?

]]>https://forum.qt.io/post/840803https://forum.qt.io/post/840803Fri, 06 Nov 2026 19:05:19 GMT<![CDATA[Reply to Checking if running as command-line (QCoreApplication) or GUI on Fri, 06 Nov 2026 19:02:16 GMT]]>@Perdrix
It may depend on platform or what you mean by command line. Have you just tested linking your command line program with a piece of code which goes if (qApp) and verified the final executable is still a command-line/console application?

]]>https://forum.qt.io/post/840802https://forum.qt.io/post/840802Fri, 06 Nov 2026 19:02:16 GMT<![CDATA[Reply to Checking if running as command-line (QCoreApplication) or GUI on Fri, 06 Nov 2026 15:55:31 GMT]]>@JonB I build a GUI application which instantiates a QApplication in its main(), and a completely different piece of code is used for the command line application which creates a QCoreApplication.

So I think that qApp will work in that case?

]]>https://forum.qt.io/post/840800https://forum.qt.io/post/840800Fri, 06 Nov 2026 15:55:31 GMT<![CDATA[Reply to Checking if running as command-line (QCoreApplication) or GUI on Fri, 06 Nov 2026 12:03:38 GMT]]>@Perdrix
I imagine that is a reasonable test if you want to do a Qt call, as in: "is there a QApplication object?"

A global pointer referring to the unique application object. It is equivalent to QCoreApplication::instance(), but cast as a QApplication pointer, so only valid when the unique application object is a QApplication.

However, are you intending to use single-source with two separate compilations/links, one for GUI and one for console? Because if you are thinking you can do just one compilation/link and decide at runtime whether to run as GUI or command line you are going to stall. Under Windows at least --- which ISTR you use --- an executable is linked as either "windows" (GUI) or "console" (command-line) and you are stuck with that at runtime.

]]>https://forum.qt.io/post/840794https://forum.qt.io/post/840794Fri, 06 Nov 2026 12:03:38 GMT