Tutorials

Similarly like a friend function, class can be made a friend of another class using friend keyword.

A friend class in C++ can access the "private" and "protected" members of the class in which it is declared as a friend.

e.g:

class A{
	friend class B;
}
Class B{

}

When a class is made a friend class all the member function of that class becomes friend function. In this program all the member function of class B will be friend function of class A.

Thus any member function of class B can access the private and protected data of class A.

If B is declare friend class of A then all member function of class B can access private and protected data of class A, but member function of class A can not private & protected data of class B.

#include<conio.h>
#include<iostream.h>
class Number{
      int x,y;
      public:
	     void setNumber(int i,int j){
	      x=i;
	      y=j;
	     }
	     void show()
	     {
	      cout<<"\nx = "<<x<<"\t"<<"y = "<<y;
	     }
	     friend class min;
};
class min{
    public:
	   int minof(Number &n);
};
int min::minof(Number &n)
{
   if(n.x>n.y)
	return n.x;
   else
	return n.y;
}
void main()
{
 Number n;
 min m;
 clrscr();
 n.setNumber(5,6);
 n.show();
 int a=m.minof(n);
 cout<<"\n Maximum = "<<a;
 getch();
}

O/P

X=5
Y=6
Maximum= 6