I've tried a couple different ways to do this without success. Just trying to see if I overlooked anything?

The way I've been doing nested structures is like this:
Code:
struct a
  {
  /* blah blah blah */
  };
struct b
  {
  /* whatever */
  };
struct c
  {
   struct a z;
   struct b y;
  };
And then assign a variable for struct c in the main program. Is there a way to do it all at once? Such as:
Code:
struct c
  {
  struct a
    {
    /* blah blah blah */
    };
   struct b
    {
     /* whatever */
     };
   };
I tried to do it like above and the compiler doesn't complain until I try to access the variables inside of a. Any tips/suggestions?