Program both as Console and GUI [duplicate]

Answer 1

Windows has different values in executable's header for console and UI application (see more details here). So it seems to be impossible to make the same executable to work in both modes.

As an alternative, you can open a console in you UI app, but it will be new console, not the one you've started app from.

Answer 2

AttachConsole() may be used to get a hold of the parents console. E.g. if the application is started from a cmdline shell, AllocConsole() can be avoided:

if not AttachConsole(ATTACH_PARENT_PROCESS)
then AllocConsole;

More info here: http://msdn.microsoft.com/en-us/library/windows/desktop/ms681952(v=vs.85).aspx

Answer 3

http://blogs.msdn.com/oldnewthing/archive/2009/01/01/9259142.aspx

Answer 4

IMO, the best approach here is to have non-visual classes that actually do the work of the program. Then you can call that from a GUI program, and you can also call it from a separate command line program. Both programs are just wrappers around the functionality of your class(es).

This forces the design to be clean too - your classes necessarily are separated from the GUI layer of your application.

Answer 5

On Windows this is a little bit tricky. Actually the distinction between a console application and a GUI one is a single flag in the PE header. You can easily write console applications that create windows but that way you always have the console window around (you could hide it, though, but that wouldn't be nice when people run your program from cmd).

You can, however write a GUI application that creates a console if it needs to, using the AllocConsole function:

A process can be associated with only one console, so the AllocConsole function fails if the calling process already has a console. A process can use the FreeConsole function to detach itself from its current console, then it can call AllocConsole to create a new console or AttachConsole to attach to another console.

If the calling process creates a child process, the child inherits the new console.

AllocConsole initializes standard input, standard output, and standard error handles for the new console. The standard input handle is a handle to the console's input buffer, and the standard output and standard error handles are handles to the console's screen buffer. To retrieve these handles, use the GetStdHandle function.

This function is primarily used by graphical user interface (GUI) application to create a console window. GUI applications are initialized without a console. Console applications are initialized with a console, unless they are created as detached processes (by calling the CreateProcess function with the DETACHED_PROCESS flag).

However, when run from cmd this will likely cause another console window to appear instead of re-using the existing one. I don't know whether a good solution exists there.