#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("sizeof(p) = %lu\n", sizeof(p));
  printf("sizeof(*p) = %lu\n", sizeof(*p));

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

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

  printf("ARRAY_SIZE * sizeof(int) = %lu\n", ARRAY_SIZE*sizeof(int));

  // dirty the memory pointed at by p then free it
  for (int i=0; i<ARRAY_SIZE; i++) p[i] = i;
  free(p);

  // allocate an array again and print its contents
  // (malloc does not initialize)
  p = (int*)malloc(ARRAY_SIZE * sizeof(int));
  if ( p == NULL ) error(1, 0, "Out of memory!");
  for (int i=0; i<ARRAY_SIZE; i++)  printf("p[%d] = %d\n", i, p[i]);

  return 0;
}