OFFSETOF
#define OFFSETOF(str, field) offsetof(str, field)
#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))