Shorthand or inline method of initializing members of nested SDL_Rect struct in C, via function-CodePudding

I'm trying to improve the readability and overall organization of my project(s) which use SDL2. I'm trying to understand what I'm doing wrong when it comes to initializing members of a nested struct when it comes to SDL_Rect.

This is what I'm trying to achieve:

struct gfx {
  SDL_Rect rect;
} gfx;

void example()
{
  gfx.rect = {0,0,1280,720};

  return;
}

However, this produces an "Expression Expected" error.

So, what I have been doing, which does work, but just creates a ton of clutter, is this:

struct gfx {
  SDL_Rect rect;
} gfx;

void example()
{
  gfx.rect.x = 0;
  gfx.rect.y = 0;
  gfx.rect.w = 1280;
  gfx.rect.h = 720;

  return;
}

Is it possible to achieve a shorthand version as shown, or is this just the way it needs to be?

Here is a link to the definition of the SDL_Rect struct: https://www.libsdl.org/release/SDL-1.2.15/docs/html/sdlrect.html

I'm using xCode 12.5.1, writing the project in C, with Clang, C99.

CodePudding user response：

This seems to work:

gfx x = {.rect = {.x = 0, .y = 0, .w = 1280, .h = 720}};

This seems to work too, but it may result in extra copy

SDL_Rect r = {.x = 0, .y = 0, .w = 1280, .h = 720};
gfx y = {.rect = r};

most examples here initialize struct members by names.

CodePudding user response：

You can use the compound literal syntax to achieve something similar:

gfx.rect = (SDL_Rect){0,0,1280,720};

This has a little overhead of creating an extra local object of type SDL_Rect and copying it into gfx.rect.

For reference: C11 Standard draft, 6.5.2.5 Compound Literals