SDL2 confusion with pointers c

Question

I'm trying to program a basic game with SDL2 library and I am getting a little bit confused with a basic concept.

Basically I would like to make a function:

void quit_clean (SDL_Window *window, SDL_Renderer *renderer)
{
 if (renderer != NULL)
        SDL_DestroyRenderer(renderer);
 if (window != NULL)
        SDL_DestroyWindow(window);

 exit(EXIT_FAILURE);
}

I would call this function each time there is an error so I can free the renderer and the window properly before to quit the program e.g.

texture = SDL_CreateTextureFromSurface(renderer, tmp);
if(texture==NULL){
      printf ("SDL_CreateTextureFromSurface Error: : %s\n", SDL_GetError());
      quit_clean (&window, &renderer);
}

Where I am getting confused is if I need to call this function from another function how does it work ?

To be precise I would have:

1. My main() function where I create my *window and my *renderer
2. a new my_function() called from main() in which I would among other stuffs create a texture from a surface and test errors
3. and finally my quit_clean() function called from my_function() in case of error.

The way I see it, in order to pass my window and my renderer from main() to quit_clean() using my_function() the prototypes would be then:

void my_function (SDL_Window **window, SDL_Renderer **renderer);
void quit_clean (SDL_Window ***window, SDL_Renderer ***renderer);

Am I correct or not? If yes then how could I call this function from main() if needed.

If I call "quit_clean (&window, &renderer);" from my main() the types are not correct anymore then.

Or maybe I could create pointers from window and renderer and pass those pointers to quit_clean(). I don't know I'm confused, I'm not sure if my thought process is correct.

Do you have any tips for this kind of situation?

Answer 1

You don't need the double pointer as arguments to your functions:

int my_function (SDL_Window *window, SDL_Renderer *renderer);
int quit_clean (SDL_Window *window, SDL_Renderer *renderer);

As you might have noticed, i've added a return type (int), because every function should return a result, indicating success or failure.

Secondly, it would be better not to call the quit_clean function from other functions, instead, if you encounter an error in for e.g. my_function, return an error and call the quit_clean function in the main function.

Like this:

int main() 
{
    SDL_Window *window = NULL; 
    SDL_Renderer *renderer = NULL;

    window = SDL_CreateWindow(...); 

    if (window) {

        renderer = SDL_CreateRenderer(window, ...);

        if (renderer) {

            int err = my_function(window, renderer);

            if (!err) { //success: 0, error: -1
                //do what is needed to be done
            }

        }

    }

    //finally clean up, 
    //no matter the case (either due to error or program termination)
    quit_clean(window, renderer);

    return 0;
}

In the quit_clean function you have to check the passed arguments (although i think that SDL checks them too, but better than sorry):

int quit_clean (SDL_Window *window, SDL_Renderer *renderer)
{
    //other cleanup first

    //finally
    if (renderer != NULL)
        SDL_DestroyRenderer(renderer);
    if (window != NULL)
        SDL_DestroyWindow(window);
    SDL_Quit();
}

And for clarity an example of my_function:

int my_function (SDL_Window *window, SDL_Renderer *renderer)
{
    if (some_condition_does_not_hold)
        return -1;

    //do your stuff
    //never call quit_clean if something goes wrong, return either -1 or
    //some other (previously defined) negative error number

    //finally
    return 0; //success
}