Why declare a pointer in SDL before initializing SDL?

问题

In this code, I see that they declare a pointer before initializing SDL:

int main(int argc, char* argv[]) {

    SDL_Window *window;                    // Declare a pointer

    SDL_Init(SDL_INIT_VIDEO);              // Initialize SDL2

    // Create an application window with the following settings:
    window = SDL_CreateWindow(
        "An SDL2 window",                  // window title
        SDL_WINDOWPOS_UNDEFINED,           // initial x position
        SDL_WINDOWPOS_UNDEFINED,           // initial y position
        640,                               // width, in pixels
        480,                               // height, in pixels
        SDL_WINDOW_OPENGL                  // flags - see below
);

(full code can be found here)

Wouldn't it be more organized to declare the pointer right before you create a window, just so it would be neater and more organized? Why declare it beforehand?

If I would take a guess, it's good to just have all the pointers in one area, so you can see all the pointers at one time. Or is it just a good habit to get used to?

The habit of declaring pointers at the beginning of int main(). (I've also seen this happen in other source programs, from example programs)

回答1:

There is no technical reason why you need to declare a pointer before SDL_Init. Declaring a pointer variable carries no implications with it, it just reserves space on the stack for that pointer. It could just as easily be declared after SDL_Init, or as part of the statement that calls SDL_CreateWindow.

I honestly don't know why they put it that way in the docs.

来源：https://stackoverflow.com/questions/51296729/why-declare-a-pointer-in-sdl-before-initializing-sdl