C++ / SDL Debugging with console window

Question

I am playing around with some OpenGL, using SDL to handle the window / input etc. Currently I am displaying any information I want to see to a HUD. Well, this is getting over-cumbersome, and I was wondering if there is a simple way to open up a separate console window to report this information to me. I am still new to C++ so go easy on me if this is an obvious one.

Answer 1

The following code is for Windows. I always find it handy to keep around the ability to create a console window on demand:

    int hConHandle;
    intptr_t lStdHandle;
    CONSOLE_SCREEN_BUFFER_INFO coninfo;
    FILE *fp;

    // allocate a console for this app
    AllocConsole();

    // set the screen buffer to be big enough to let us scroll text
    GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &coninfo);
    coninfo.dwSize.Y = 500;
    SetConsoleScreenBufferSize(GetStdHandle(STD_OUTPUT_HANDLE), coninfo.dwSize);

    // redirect unbuffered STDOUT to the console
    lStdHandle = (intptr_t)GetStdHandle(STD_OUTPUT_HANDLE);
    hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
    fp = _fdopen( hConHandle, "w" );
    *stdout = *fp;
    setvbuf( stdout, NULL, _IONBF, 0 );

    // redirect unbuffered STDIN to the console
    lStdHandle = (intptr_t)GetStdHandle(STD_INPUT_HANDLE);
    hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
    fp = _fdopen( hConHandle, "r" );
    *stdin = *fp;
    setvbuf( stdin, NULL, _IONBF, 0 );

    // redirect unbuffered STDERR to the console
    lStdHandle = (intptr_t)GetStdHandle(STD_ERROR_HANDLE);
    hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
    fp = _fdopen( hConHandle, "w" );
    *stderr = *fp;
    setvbuf( stderr, NULL, _IONBF, 0 );

    // make cout, wcout, cin, wcin, wcerr, cerr, wclog and clog point to console as well
    std::ios::sync_with_stdio();

    //Keep our window in focus
    SetForegroundWindow(m_hWnd);                        // Slightly Higher Priority
    SetFocus(m_hWnd);                                   // Sets Keyboard Focus To The Window

This code assumes that the HWND is in a variable called m_hWnd; it's copied from a class wrapper I use. How you get the HWND from SDL is up to you, however.

To free the console, call this:

FreeConsole();

AllocConsole and FreeConsole are Win32 API functions.

Answer 2

In Linker -> System in your project's properties, check that the SubSystem is "Console (/SUBSYSTEM:CONSOLE)". That causes a separate console window to be brought up when you run your program. If your current entry point isn't main, then you'll need to change it to that if you do this though.