The document discusses friend functions and friend classes in C++. A friend function has access to all private and protected members of a class but must be called with an object passed as a parameter rather than through an object. A friend function violates data hiding and encapsulation. A friend class allows member functions of one class to access private members of another class, providing similar functionality to a friend function but through class members instead of standalone functions. Code snippets demonstrate declarations of friend functions and classes.

1. FRIEND FUNCTION & FRIEND
CLASS
Abhishek Wadhwa
Bharati Vidyapeeth‟s Institute of Computer Application
Management(BVICAM)

2. Who is a Friend?
A friend is one who has access to all your
“PRIVATE” stuff

3. What is Friend Function?
 A non member function
 Has access to all the Private and Protected
Members of a class

4. How is it different from normal
function?
 A member is access “through” the object
Ex : sample object;
object.getdata();
 Whereas A Friend function requires object to
be passed by value or by reference as a
parameter
Ex : void getdata(sample object);

5. Code Snippet:
class demo
{
int x;
public:
demo(int xx)
{
x=xx;
}
friend void display(demo); //Declaration inside the class
};
void display(demo dd1) //Definition outside the class
{
cout<<dd1.x;
}

6. What are its Disadvantages?
 Violates Data Hiding
 Violates encapsulation

7. Friend class
 Provides the same feature as that of Friend
Fn.
 Allows „member fn” of one class to friend of
other class
 i.e. the private member of the class will be
accessible to the friend class

8. Code snippet:
class xxx
{
int x;
public:
xxx(int xx)
{
x=xx;
}
friend class yyy;
};
class yyy
{
public:
void f1(xxx obj)
{cout<<“x=”<<obj.x;}
};

9. Thank You
www.programming90.blogspot.in
www.ipnotes.blogspot.in
Abhishek wadhwa