#include struct s { char c; union { short i[3]; int d; } n; struct { struct s * hd; struct s * tl; } l; }; char tbl[sizeof(struct s)]; /* Should be 32: char c at 0 union n at 4 because alignment = 4; sizeof = 8 struct l at 4+8=12 with alignment = 4; sizeof = 8 end of struct at 12+8=20 alignment of whole struct is 4 20 aligned to 4 -> 20 */ struct bits1 { unsigned a: 1; unsigned b: 6; }; char b1[sizeof(struct bits1)]; /* should be 1 */ struct bits2 { unsigned a: 1; unsigned b: 6; unsigned c: 28; }; char b2[sizeof(struct bits2)]; /* should be 8 */ int main() { printf("sizeof(struct s) = %d, sizeof(tbl) = %d\n", sizeof(struct s), sizeof(tbl)); printf("sizeof(struct bits1) = %d, sizeof(b1) = %d\n", sizeof(struct bits1), sizeof(b1)); printf("sizeof(struct bits2) = %d, sizeof(b2) = %d\n", sizeof(struct bits2), sizeof(b2)); return 0; }