Check if SDL Window is open

You dont specify if you are using SDL 1.2, or SDL 2. I will explain it with SDL 1.2.

When yo do a

SDL_Surface* = SDL_SetVideoMode(Params...);

to create the window, you set the pointer of the window created in your SDL_Surface* SDL variable.

The function has two returns.

If has been executed successfully, it will return the pointer of the window. If has NOT been executed successfully, it will return 'NULL';

So, yo need to check if the windows was created checking that pointer. I will copy a segment of my code in SDL:

    Window = SDL_SetVideoMode(WindowWidth, WindowHeigth,Bpp, SDL_HWSURFACE | SDL_RESIZABLE);    /// Asigno al Window el puntero asignado de la pantalla creada

    if( Window == NULL )    /// Window inicializado con error
    {
        if(Is_Open) { Log("Inicialize Window error"); } if(Is_Open) { Log(SDL_GetError()); }
        if(Is_Open) { Log("Window", Window); }
        SDL_Quit();
        exit(-1);
    }

Try to read the documentation for each function. Its not hard. Docs for SDL 1.2: https://www.libsdl.org/release/SDL-1.2.15/docs/ for SDL 2: https://wiki.libsdl.org/

And if you are using different functions you have 2 choices, make the variable of the window Global, or, passing by parameter to all your functions.

PD: Sorry for my english!