// friends can access private members, but non-friend/non-member functions
// can not access private data of a class
#include <iostream.h>

class Count  {
    friend void setX(Count &, int);  // friend declaration
public:
    Count()  {x = 0;}                // constructor
    void print()  const { cout << x << endl; }
private:
    int x;  // private data member
};

void setX(Count &c, int value) {
    c.x = value; // legal if setX is a friend of class Count
}

// void cannotSetX(Count &c, int value) {
//     c.x = value;  // error: 'Count::x' is not accessible
// }

main( )   {
    Count object;

    cout << "friend function can access private data member" << endl;
    cout << "object.x after initilized: ";
    object.print();
    cout << "object.x after friend function setX is called: ";
    setX(object, 5);   // set x with a friend
    object.print();
    cout << endl;
    cout << "include the non-friend function and see what happens" << endl;

//    cout << "non-friend can not access private data member" << endl;
//    cannotSetX(object, 10);  // cannotSet is not a friend

    getchar();
    return 0;
}