#include <iostream> 

class Bar
{
  friend class Foo;
  friend void setit(Bar& b, int n);

  int x;
  
public:
  // friend function defined in the class
  // is a global function
  friend void setit(Bar& b, int n1, int n2)
  {
    b.x = n1 + n2;
  }
};

class Foo
{
public:
  void printit(Bar b)
  {
    // we can access private members of Bar because class Foo is its friend
    std::cout << b.x << std::endl;
  }
};

void setit(Bar& b, int n)
{
  // we can access private members of Bar because this function is its friend
  b.x = n;
}

int main(int argc, char** argv) 
{ 
  Foo f;
  Bar b;

  setit(b, 25);

  f.printit(b);

  // call global function that is friend of class Bar
  setit(b, 13, 16);

  f.printit(b);

  return 0; 
}