#include <stdio.h>
#include <stdlib.h>  // for malloc
#include <error.h>

#define ARRAY_SIZE 100

#define myFree(p) { free(p);  p = NULL; }


int main(int argc, char **argv) {
  int *p;

  // what happens when we use a dangling pointer?
  p = (int*)malloc(ARRAY_SIZE * sizeof(int));
  for (int i=0; i<ARRAY_SIZE; i++) p[i] = i;
  free(p);

  printf("p[12] = %d\n", p[12]);  // this is an error!

  // What happens if we free p again?
  free(p);  // This has "undefined behavior"

  return 0;
}