minimal-struct-size-align.c

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

     min_size = sizeof (s20);
  if (min_align > __alignof__ (s20))
     min_align = __alignof__ (s20);
  if (min_size > sizeof (u20))
     min_size = sizeof (u20);
  if (min_align > __alignof__ (u20))
     min_align = __alignof__ (u20);
  if (min_size > sizeof (s21))
     min_size = sizeof (s21);
  if (min_align > __alignof__ (s21))
     min_align = __alignof__ (s21);
  if (min_size > sizeof (u21))
     min_size = sizeof (u21);
  if (min_align > __alignof__ (u21))
     min_align = __alignof__ (u21);
  if (min_size > sizeof (s22))
     min_size = sizeof (s22);
  if (min_align > __alignof__ (s22))
     min_align = __alignof__ (s22);
  if (min_size > sizeof (u22))
     min_size = sizeof (u22);
  if (min_align > __alignof__ (u22))
     min_align = __alignof__ (u22);
  if (min_size > sizeof (s23))
     min_size = sizeof (s23);
  if (min_align > __alignof__ (s23))
     min_align = __alignof__ (s23);
  if (min_size > sizeof (u23))
     min_size = sizeof (u23);
  if (min_align > __alignof__ (u23))
     min_align = __alignof__ (u23);
  if (min_size > sizeof (s24))
     min_size = sizeof (s24);
  if (min_align > __alignof__ (s24))
     min_align = __alignof__ (s24);
  if (min_size > sizeof (u24))
     min_size = sizeof (u24);
  if (min_align > __alignof__ (u24))
     min_align = __alignof__ (u24);
  if (min_size > sizeof (s25))
     min_size = sizeof (s25);
  if (min_align > __alignof__ (s25))
     min_align = __alignof__ (s25);
  if (min_size > sizeof (u25))
     min_size = sizeof (u25);
  if (min_align > __alignof__ (u25))
     min_align = __alignof__ (u25);
  if (min_size > sizeof (s26))
     min_size = sizeof (s26);
  if (min_align > __alignof__ (s26))
     min_align = __alignof__ (s26);
  if (min_size > sizeof (u26))
     min_size = sizeof (u26);
  if (min_align > __alignof__ (u26))
     min_align = __alignof__ (u26);
  if (min_size > sizeof (s27))
     min_size = sizeof (s27);
  if (min_align > __alignof__ (s27))
     min_align = __alignof__ (s27);
  if (min_size > sizeof (u27))
     min_size = sizeof (u27);
  if (min_align > __alignof__ (u27))
     min_align = __alignof__ (u27);
  if (min_size > sizeof (s28))
     min_size = sizeof (s28);
  if (min_align > __alignof__ (s28))
     min_align = __alignof__ (s28);
  if (min_size > sizeof (u28))
     min_size = sizeof (u28);
  if (min_align > __alignof__ (u28))
     min_align = __alignof__ (u28);
  if (min_size > sizeof (s29))
     min_size = sizeof (s29);
  if (min_align > __alignof__ (s29))
     min_align = __alignof__ (s29);
  if (min_size > sizeof (u29))
     min_size = sizeof (u29);
  if (min_align > __alignof__ (u29))
     min_align = __alignof__ (u29);
  if (min_size > sizeof (s30))
     min_size = sizeof (s30);
  if (min_align > __alignof__ (s30))
     min_align = __alignof__ (s30);
  if (min_size > sizeof (u30))
     min_size = sizeof (u30);
  if (min_align > __alignof__ (u30))
     min_align = __alignof__ (u30);
  if (min_size > sizeof (s31))
     min_size = sizeof (s31);
  if (min_align > __alignof__ (s31))
     min_align = __alignof__ (s31);
  if (min_size > sizeof (u31))
     min_size = sizeof (u31);
  if (min_align > __alignof__ (u31))
     min_align = __alignof__ (u31);
  if (min_size > sizeof (s32))
     min_size = sizeof (s32);
  if (min_align > __alignof__ (s32))
     min_align = __alignof__ (s32);
  if (min_size > sizeof (u32))
     min_size = sizeof (u32);
  if (min_align > __alignof__ (u32))
     min_align = __alignof__ (u32);
  if (min_size > sizeof (s33))
     min_size = sizeof (s33);
  if (min_align > __alignof__ (s33))
     min_align = __alignof__ (s33);
  if (min_size > sizeof (u33))
     min_size = sizeof (u33);
  if (min_align > __alignof__ (u33))
     min_align = __alignof__ (u33);
  if (min_size > sizeof (s34))
     min_size = sizeof (s34);
  if (min_align > __alignof__ (s34))
     min_align = __alignof__ (s34);
  if (min_size > sizeof (u34))
     min_size = sizeof (u34);
  if (min_align > __alignof__ (u34))
     min_align = __alignof__ (u34);
  if (min_size > sizeof (s35))
     min_size = sizeof (s35);
  if (min_align > __alignof__ (s35))
     min_align = __alignof__ (s35);
  if (min_size > sizeof (u35))
     min_size = sizeof (u35);
  if (min_align > __alignof__ (u35))
     min_align = __alignof__ (u35);
  if (min_size > sizeof (s36))
     min_size = sizeof (s36);
  if (min_align > __alignof__ (s36))
     min_align = __alignof__ (s36);
  if (min_size > sizeof (u36))
     min_size = sizeof (u36);
  if (min_align > __alignof__ (u36))
     min_align = __alignof__ (u36);
  if (min_size > sizeof (s37))
     min_size = sizeof (s37);
  if (min_align > __alignof__ (s37))
     min_align = __alignof__ (s37);
  if (min_size > sizeof (u37))
     min_size = sizeof (u37);
  if (min_align > __alignof__ (u37))
     min_align = __alignof__ (u37);
  if (min_size > sizeof (s38))
     min_size = sizeof (s38);
  if (min_align > __alignof__ (s38))
     min_align = __alignof__ (s38);
  if (min_size > sizeof (u38))
     min_size = sizeof (u38);
  if (min_align > __alignof__ (u38))
     min_align = __alignof__ (u38);
  if (min_size > sizeof (s39))
     min_size = sizeof (s39);
  if (min_align > __alignof__ (s39))
     min_align = __alignof__ (s39);
  if (min_size > sizeof (u39))
     min_size = sizeof (u39);
  if (min_align > __alignof__ (u39))
     min_align = __alignof__ (u39);
  if (min_size > sizeof (s40))
     min_size = sizeof (s40);
  if (min_align > __alignof__ (s40))
     min_align = __alignof__ (s40);
  if (min_size > sizeof (u40))
     min_size = sizeof (u40);
  if (min_align > __alignof__ (u40))
     min_align = __alignof__ (u40);
  if (min_size > sizeof (s41))
     min_size = sizeof (s41);
  if (min_align > __alignof__ (s41))
     min_align = __alignof__ (s41);
  if (min_size > sizeof (u41))
     min_size = sizeof (u41);
  if (min_align > __alignof__ (u41))
     min_align = __alignof__ (u41);
  if (min_size > sizeof (s42))
     min_size = sizeof (s42);
  if (min_align > __alignof__ (s42))
     min_align = __alignof__ (s42);
  if (min_size > sizeof (u42))
     min_size = sizeof (u42);
  if (min_align > __alignof__ (u42))
     min_align = __alignof__ (u42);
  if (min_size > sizeof (s43))
     min_size = sizeof (s43);
  if (min_align > __alignof__ (s43))
     min_align = __alignof__ (s43);
  if (min_size > sizeof (u43))
     min_size = sizeof (u43);
  if (min_align > __alignof__ (u43))
     min_align = __alignof__ (u43);
  if (min_size > sizeof (s44))
     min_size = sizeof (s44);
  if (min_align > __alignof__ (s44))
     min_align = __alignof__ (s44);
  if (min_size > sizeof (u44))
     min_size = sizeof (u44);
  if (min_align > __alignof__ (u44))
     min_align = __alignof__ (u44);
  if (min_size > sizeof (s45))
     min_size = sizeof (s45);
  if (min_align > __alignof__ (s45))
     min_align = __alignof__ (s45);
  if (min_size > sizeof (u45))
     min_size = sizeof (u45);
  if (min_align > __alignof__ (u45))
     min_align = __alignof__ (u45);
  if (min_size > sizeof (s46))
     min_size = sizeof (s46);
  if (min_align > __alignof__ (s46))
     min_align = __alignof__ (s46);
  if (min_size > sizeof (u46))
     min_size = sizeof (u46);
  if (min_align > __alignof__ (u46))
     min_align = __alignof__ (u46);
  if (min_size > sizeof (s47))
     min_size = sizeof (s47);
  if (min_align > __alignof__ (s47))
     min_align = __alignof__ (s47);
  if (min_size > sizeof (u47))
     min_size = sizeof (u47);
  if (min_align > __alignof__ (u47))
     min_align = __alignof__ (u47);
  if (min_size > sizeof (s48))
     min_size = sizeof (s48);
  if (min_align > __alignof__ (s48))
     min_align = __alignof__ (s48);
  if (min_size > sizeof (u48))
     min_size = sizeof (u48);
  if (min_align > __alignof__ (u48))
     min_align = __alignof__ (u48);
  if (min_size > sizeof (s49))
     min_size = sizeof (s49);
  if (min_align > __alignof__ (s49))
     min_align = __alignof__ (s49);
  if (min_size > sizeof (u49))
     min_size = sizeof (u49);
  if (min_align > __alignof__ (u49))
     min_align = __alignof__ (u49);
  if (min_size > sizeof (s50))
     min_size = sizeof (s50);
  if (min_align > __alignof__ (s50))
     min_align = __alignof__ (s50);
  if (min_size > sizeof (u50))
     min_size = sizeof (u50);
  if (min_align > __alignof__ (u50))
     min_align = __alignof__ (u50);
  if (min_size > sizeof (s51))
     min_size = sizeof (s51);
  if (min_align > __alignof__ (s51))
     min_align = __alignof__ (s51);
  if (min_size > sizeof (u51))
     min_size = sizeof (u51);
  if (min_align > __alignof__ (u51))
     min_align = __alignof__ (u51);
  if (min_size > sizeof (s52))
     min_size = sizeof (s52);
  if (min_align > __alignof__ (s52))
     min_align = __alignof__ (s52);
  if (min_size > sizeof (u52))
     min_size = sizeof (u52);
  if (min_align > __alignof__ (u52))
     min_align = __alignof__ (u52);
  if (min_size > sizeof (s53))
     min_size = sizeof (s53);
  if (min_align > __alignof__ (s53))
     min_align = __alignof__ (s53);
  if (min_size > sizeof (u53))
     min_size = sizeof (u53);
  if (min_align > __alignof__ (u53))
     min_align = __alignof__ (u53);
  printf ("min struct/union size =%d\n", min_size);
  printf ("min struct/union align=%d\n", min_align);
  return 0;
}