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

#define ARRAY_SIZE 100

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

  printf("pre-malloc:\n");
  printf("p = %p\n", p);

  p = (int*)malloc(ARRAY_SIZE * sizeof(int));
  if ( p == NULL ) error(1, 0, "Out of memory!");

  printf("\npost-malloc:\n");
  printf("p = %p\n", p);

  free(p);

  printf("\npost-free:\n");
  printf("p = %p\n", p);

  return 0;
}