#include <stdio.h>

struct combined {
  int x;
  int *p;
};

char f(char x) {
  char y = 7;
  fprintf(stdout, "local x lives at %x\n", &x);
  fprintf(stdout, "local y lives at %x\n\n", &y);
  return x+y;
}

int main(int argc, char **argv) {
  char x = 'a';
  char *p = &x;
  char **pp = &p;
  fprintf(stdout, "x lives at %x\n", &x);
  fprintf(stdout, "p lives at %x\n", &p);
  fprintf(stdout, "pp lives at %x\n\n", &pp);

  fprintf(stdout, "&x - 1 is: %x\n", (&x - 1));
  fprintf(stdout, "&x + 1 is: %x\n", (&x + 1));
  fprintf(stdout, "&x - 15 is: %x\n\n", (&x - 15));

  fprintf(
    stdout,
    "Memory near x:\n%d %d %d %d\n%d %d %d %d\n%d %d %d %d\n%d %d %d %d\n\n",
    *(&x - 0),
    *(&x - 1),
    *(&x - 2),
    *(&x - 3),
    *(&x - 4),
    *(&x - 5),
    *(&x - 6),
    *(&x - 7),
    *(&x - 8),
    *(&x - 9),
    *(&x - 10),
    *(&x - 11),
    *(&x - 12),
    *(&x - 13),
    *(&x - 14),
    *(&x - 15)
  );

  fprintf(stdout, "argv lives at %x\n", argv);
  fprintf(stdout, "*argv lives at %x\n\n", *argv);

  x = f(x);

  fprintf(stdout, "f lives at %x\n\n", &f);

  int *addr = &f;
  *addr = 3;

  fprintf(stdout, "A character is %d bytes.\n", sizeof(char));
  fprintf(stdout, "An integer is %d bytes.\n", sizeof(int));
  fprintf(stdout, "A pointer is %d bytes.\n", sizeof(int*));
  fprintf(stdout, "Our struct (int + pointer) is %d bytes.\n", sizeof(struct combined));
}