The document discusses the concept of friend functions in C++, which allow non-member functions to access private data of multiple classes. It explains the syntax, characteristics, and usage of friend functions, including the ability to declare a class as a friend. The document also presents a real-life analogy to clarify the concept.

1. OOPC
FRIEND FUNCTION
Dhananjaysinh Jhala
SY CE-1, Batch B
170410107027

2. FRIEND FUNCTION
While learning C++, we have emphasized on the fact that private members
cannot be accessed from outside the class i.e. A non member function cannot
have access to the private data of a class.
However, there could arise a situation where we would like 2 classes to share
a particular function.
 In such situations, C++ allows a common function to be made friendly with
both the classes, allowing the function to have access to the private members
of these classes outside the class.
This can be seen as a real life analogy, where is a person would like to come
in your house, then you need to declare him as your friend so that I can access
your private resources.

3.  Syntax of the friend function is given below
 Function declared with the keyword friend is called friend
function.

4. Some special characteristics of friend function are as
follows:
It is not in the scope of the class to which it has been declared
as friend.
It can be invoked like a normal function without any object
needed.
Unlike Member function, it cannot access the member names
directly, and has to use object name and dot membership
operator with each member name.
It can be declared as public or private without affecting its
meaning
Usually it has object as arguments

5. Member functions of one class can be friend functions of another
class. In such cases, they are designed using the scope resolution
operator.
We can also declared the class as a friend class.

6. PROGRAM TO FIND AVERAGE USING FRIEND FUNCTION

8. OUTPUT