在C中传递“直接”结构作为函数

Question

I have a simple question about structures in C.

I have this struct and this function:

struct Vec2
{
  int x;
  int y;
}

void draw(Sprite* sprite, struct Vec2 pos);

Is there anyway to do the equivalent in c++?

draw(foo, new Vec2(10, 20));

I tried this but the compiler doesn't agree with me:

draw(foo, {10, 20} );

Anybody to help ?

Edit: I use Visual C++ 2008 Express in C++ mode, but for my school I must code in straight C, not C++

Answer 1

If your compiler supports C99 or later, you can use a compound literal :

draw(foo, (struct Vec2){10, 20});

or, if you want to be more explicit about the member names:

draw(foo, (struct Vec2){.x = 10, .y = 20});

(Note that Microsoft's C compiler doesn't support C99, which could limit the portability of your code.)

Answer 2

What I usually do is :

struct Vec2 make_Vec2( int x, int y ) {
  struct Vec2 vec;
  vec.x = x; vec.y = y;
  return vec;
}

...
draw( foo, make_Vec2( 10, 20 ) );

Answer 3

Just adding a working example with @Keith Thompson's answer:

#include <stdio.h>
#include<string.h>
struct two{
 int x;
 int y;
};
draw(struct two t){
    printf("\nx=%d y=%d\n", t.x, t.y);
}
int main(){
 draw((struct two){1,2});
 draw((struct two){.y = 1, .x = 2});
} 

Output:

:~$ ./a.out 

 x=1 y=2

 x=2 y=1