text: #include <stdio.h>
  #include <assert.h>
  
  void pointer_to_pointer ()
  {
      int i = 1;
      int *p = &i;
      int **r = &p;
  
      assert(*r == p);
      assert(**r == *p);
  
      printf("Address of p: %p\n", r);
      printf("Address of i: %p\n", *r);
      printf("Value of i: %d\n", **r);
  }
  
  int main(int argc, char** argv) {
      pointer_to_pointer();
  }