realloc.c

#include <stdio.h>
#include <stdlib.h>

#define IGNORE(X) ((void)X)
#define MAX_ALLOC (1024 * 1024)
#define MIN_ALLOC (128)

int main(int argc, char * argv[]) {
  IGNORE(argc);
  IGNORE(argv);

  void * ptr = malloc(MIN_ALLOC);

  for (int i = 0; i < 100; i++) {
    size_t realloc_sz = arc4random_uniform(MAX_ALLOC);
    void * new_ptr = realloc(ptr, realloc_sz);

    if (NULL == new_ptr) {
      printf("Realloc of size: %lu. Realloc failed!\n", realloc_sz);
    } else if (new_ptr != ptr) {
      printf("Realloc of size: %lu. Pointer changed: (%p -> %p)\n", realloc_sz, ptr, new_ptr);
      ptr = new_ptr;
    } else {
      printf("Realloc of size: %lu. Pointer is the same: (%p)\n", realloc_sz, ptr);
    }
  }

  return 0;
}

Thank you both (again)! At some point, I owe you both a beverage of choice.