Comparing the Cost of Different Multiple-return Techniques in C(spin.atomicobject.com)

    /* okay */
    struct monster {
      unsigned id;
      int x, y, hp;
      /* etc. */
    };
    /* better */
    struct point { int x, y; };
    struct monster {
      unsigned id;
      struct point pos;
      int hp;
    };

    struct bad_monster {
      struct monster base;
      int badness; /* your imagination is the limit. */
    };

    /* this is safe */
    struct bad_monster bad;
    struct monster *some_monster = (struct monster *)&bad; /* equivalently &bad.base */
    some_function_expecting_a_monster(some_monster);
    /* only safe if it was originally a struct bad_monster */
    struct bad_monster *bad_ptr = (struct bad_monster *)some_monster;