Accessing child variables through higher level structures

Question

If I have these structures:

typedef struct { int x; } foo;
typedef struct { foo f; } bar;

Normally you would access x through

Answer 1

C: Highly unrecommended, but doable:

#include 

#define BAR_STRUCT struct { int x; }

typedef BAR_STRUCT bar;

typedef struct {
    union {
        bar b;
        BAR_STRUCT;
    };
} foo;

int main() {
  foo f;
  f.x = 989898;
  printf("%d %d", f.b.x, f.x);

  return 0;
}

Anonymous structs are a widly-spread extension in standards before C11.

C++: The same as in C, you can do here but anonymous structs are not part of any C++ standard, but an extension. Better use inheritance, or do not use this shortcut at all.

Of course, do not use something like #define x b.x)).