#include <stdio.h> static struct sss{ long f; char :0; int i; } sss; #define _offsetof(st,f) ((char *)&((st *) 16)->f - (char *) 16) int main (void) { printf ("+++char zerofield inside struct starting with long:\n"); printf ("size=%d,align=%d\n", sizeof (sss), __alignof__ (sss)); printf ("offset-long=%d,offset-last=%d,\nalign-long=%d,align-last=%d\n", _offsetof (struct sss, f), _offsetof (struct sss, i), __alignof__ (sss.f), __alignof__ (sss.i)); return 0; }