Question

If there’s a structure with a pointer to a struct declared within it, how do you determine the size of the sub-struct?

typedef struct myStruct {
  int member;
  struct subStruct {
    int a;
    int b;
  } *subStruct_t;
} myStruct_t;

How do you allocate space for the subStruct_t pointer? I was thinking something along the lines of

myStruct_t M;
M.subStruct_t = calloc(1,sizeof(myStruct_t.subStruct_t);

but it obviously doesn’t work. Any ideas?

Answer 1

M.subStruct_t = calloc(1,sizeof(*M.subStruct_t));

Note: allocate for the size of the structure, not for the pointer