Programming tutorial for understanding "Smart Pointers".

Smart Pointers :
“In C++, an object that implements the functionality of a pointer and additionaly performs some action whenever an object is accessed through it. Smart pointers are implemented by overloading the pointer-derefrence(->) operator”.

above is about smart pointers,
but
how to overload the -> operator?
how to implement a “smart pointers”?
and are “smart pointers” useful?
are the FAQ of “smart pointers”.
in this part I show that how to overload the -> operator by this example:

class sp1
  {
       public:
           int data;
           sp1* operator ->() { return this;};
  };

  int main()
  {
       sp1 t;
       cin >> t.data;
       cout << t->data;
  }

see that (->) operator work the same as (.) operator.
NOTE:
(.) oprator can’t be overloaded.
GoodLuck.