this is a gcc file, you can download it and learn its usetility, for further detail please look at t

				#include 								class c{				public:				  char f;				};								class c2{				public:				  long double f2;				};												static class sss: public c, public c2{				public:				  char m;				} sss;								#define _offsetof(st,f) ((char *)&((st *) 16)->f - (char *) 16)								int main (void) {				  printf ("++Class with char inhereting classes with char & longdouble:\n");				  printf ("size=%d,align=%d\n", sizeof (sss), __alignof__ (sss));				  printf ("offset-f=%d,offset-f2=%d,offset-m=%d,\nalign-f=%d,align-f2=%d,align-m=%d\n",				          _offsetof (class sss, f), _offsetof (class sss, f2), _offsetof (class sss, m),				          __alignof__ (sss.f), __alignof__ (sss.f2), __alignof__ (sss.m));				  return 0;				}