Nested Friends c++ February 12, 2010

[..from Eckel c++]
Making a structure(or class) nested doesnot automatically give it access to private members.To accomplish this,we must follow a particular form, first declare (without defining ) the nested structure ,then declare it as s friend ,and finally define the structure.The structure definition must be separate from the friend declaration ,otherwise it would be seen by the compiler as a non-member.

Friend c++ demonstration February 12, 2010

[..from C++ Eckel]

//Friend -demonstration
#include<iostream>
using namespace std;

struct X;

struct Y{
   void f(X*);
};

struct X{
   private:
     int i;
   public:
     void initialize();
     friend void g(X*,int);//global friend
     friend void Y::f(X*);//struct member friend
     friend struct Z; //entire struct is a friend
     friend void h();
};