#include <stdio.h> #pragma pack(1) struct A { char a; int b; }; #pragma pack(2) struct B { char a; int b; }; #pragma pack(4) struct C { char a; int b; }; int main(void) { printf("sizeof A = %zu\n", sizeof(struct A)); printf("sizeof B = %zu\n", sizeof(struct B)); printf("sizeof C = %zu\n", sizeof(struct C)); return 0; }