/* struct_addr.c - To prepare for our discussion of 3.5 derived data types,
 * and the completion of lab 9 (centroid) and hw1 (word stats), let's look
 * more closely at struct and their starting addresses.  How are they
 * aligned?  How are the fields aligned?
 */
#include <stdio.h>

struct place
{
  char c1;
  int i;
  char s[5];
  float f;
  double d;
  char c2;
};

main()
{
  struct place a[10];
  int i;

  printf("The struct itself has a size of %d.\n", sizeof(struct place));
  printf("Addresses of each element and field:\n");
  printf(" #    base      c1       i        s        f        d       c2\n");
  for (i = 0; i < 10; ++i)
    printf("%2d: %08x %08x %08x %08x %08x %08x %08x\n", i, &a[i], &a[i].c1,
           &a[i].i, &a[i].s, &a[i].f, &a[i].d, &a[i].c2);

  // Conclusions
  printf("sizeof(char)   = %d\n", sizeof(char));
  printf("sizeof(int)    = %d\n", sizeof(int));
  printf("sizeof(float)  = %d\n", sizeof(float));
  printf("sizeof(double) = %d\n", sizeof(double));
  printf("Space allocated to c1 = %d\n", (int)&a[0].i - (int)&a[0].c1);
  printf("Space allocated to i  = %d\n", (int)&a[0].s - (int)&a[0].i);
  printf("Space allocated to s  = %d\n", (int)&a[0].f - (int)&a[0].s);
  printf("Space allocated to f  = %d\n", (int)&a[0].d - (int)&a[0].f);
  printf("Space allocated to d  = %d\n", (int)&a[0].c2 - (int)&a[0].d);
  printf("Space allocated to c2 = %d\n", (int)&a[1].c1 - (int)&a[0].c2);
}
/* Example output:
The struct itself has a size of 40.
Addresses of each element and field:
 #    base      c1       i        s        f        d       c2
 0: 70223400 70223400 70223404 70223408 70223410 70223418 70223420
 1: 70223428 70223428 7022342c 70223430 70223438 70223440 70223448
 2: 70223450 70223450 70223454 70223458 70223460 70223468 70223470
 3: 70223478 70223478 7022347c 70223480 70223488 70223490 70223498
 4: 702234a0 702234a0 702234a4 702234a8 702234b0 702234b8 702234c0
 5: 702234c8 702234c8 702234cc 702234d0 702234d8 702234e0 702234e8
 6: 702234f0 702234f0 702234f4 702234f8 70223500 70223508 70223510
 7: 70223518 70223518 7022351c 70223520 70223528 70223530 70223538
 8: 70223540 70223540 70223544 70223548 70223550 70223558 70223560
 9: 70223568 70223568 7022356c 70223570 70223578 70223580 70223588
sizeof(char)   = 1
sizeof(int)    = 4
sizeof(float)  = 4
sizeof(double) = 8
Space allocated to c1 = 4
Space allocated to i  = 4
Space allocated to s  = 8
Space allocated to f  = 8
Space allocated to d  = 8
Space allocated to c2 = 8
*/