reducing memory usage

[coolcoder]

hello,
i am developing a project in which i have used many classes.
for creating classes i have used the new operator...example, in banana class i have an instance variable of class apples......
in header file (banana.h):

static int counter = 0;
class banana
{
  public:
  apples *ap_obj;//(apple is a class defined another file apples.cpp)
  int *index;

in banana.cpp :

class banana
{
  banana::banana(void)
  {
    ap_obj = new apples;
    index = new int;
    *index = ++counter;
  }
};

my first question is that, is my method correct (there is no run time error) in terms of memory efficiency?

my second question is that, i want to access another banana object in 1 of my methods of banana by using the index (plz note that every banana object has a unique index) variable.
for this i am thinking of using another class registry(because i want to store indexes of many classes's objects).
i am thinking of storing the pointer of 1st object of any class in my registry class.
& for accessing the pointer of any nth object of a class, i plan to use pointer arithmatics on the 1st object using the index variable...example

class registry
{
  banana *base_obj;//this value will be initialised when i create the 1st object of banana class
  banana *registry::get_nth_object(int shift);
  {
    return *(base_obj + shift);//shift is the index variable of banana class
  }
};

i want to use this get_nth_object in any class & do not want to go out of scope...hence the use of pointers

hope you people will realise this.
if there is any other efficient way of doing this by saving memory & run 'time'....then plz do tell me.

thanks a lot for reading my post :)

[helios]

I'm surprised that doesn't crash the program. banana::index isn't made to point to anywhere, so *index=foo should fail.

As for the registry class, what is the advantage of using it over regular pointers, at least for the purpose of accessing an arbitrary banana?