//Sample showing use of const and data access within class
#include <iostream>

using namespace std;

class C{
public:
  C()
  {
    data=1;
  }
  void Display(C C2) const
  {
    C2.data = 5; //note that friends and member functions of a class
                 //have access to private members of an object of
                 //that class, even though we are "in" C1 we can 
                 //access private data of C2
    cout<<"C1 data:"<<data<<" C2 data:"<<C2.data<<endl;
  }
private:
  int data;
};


int main()
{
  C C1,C2;
  C1.Display(C2);
}

/* Try:
   Changing C1's data in Display
   Adding const for C2 as parameter to Display
*/