带有预处理指令的指针

Question

Working on a code I've seen this:

#define X(i)        ((array[i]).x[0])
#define Y(i)        ((array[i]).y[0])

typedef struct {
  int x[2];
  int y[2];
} coord_t;

coord_t* array = malloc(sizeof(coord_t)* 10);
int myX = X(5);

This makes the access to array almost hardcoded with X and Y preprocessor directives. What I would like to do is to pass the pointer to the preprocessor directive, something like:

#define X(myarray,i) myarray[i].x[0]

where myarray could be any coord_t pointer:

coord_t* a = malloc(sizeof(coord_t)* 4);
coord_t* b = malloc(sizeof(coord_t)* 12);

int myX = X(a,1);
int myotherX = X(b,6);

I've done this, and it compiles without any errors however I am not getting the same results. My question is, can I #define X in this way?

Answer 1

#define X(myarray,i) myarray[i].x[0]