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.

Answer 3

If you're running from a command line and use printf() you should see messages logged out to your terminal window. Otherwise you could log to a file and use tail -f on *nix style boxes to view the output as it appears.

What environment are you using? Most IDEs will show this output in their debug output windows as well.