Advanced-C++/C2/Friend-Function/English

Title of script: Friend function in C++

Author: Ashwini Patil

Keywords: friend function, C++, Video tutorial.

Visual Cue	Narration
Slide 1	Welcome to the spoken tutorial on friend function in C++.
Slide 2	In this tutorial we will learn, Friend function. We will do this with the help of examples.
Slide 3	To record this tutorial, I am using Ubuntu OS version 11.10 g++ compiler v. 4.6.1
Slide 4-5	We know, the private data is not accessible outside the class. To access the private data we use friend function. A friend function is not a member of the class. The function can be invoked without using an object. The argument passed in the friend function is used as its object.
Slide 6	Declaration of a friend function friend return_type function_name( class_name object) friend keyword is used to declare a friend function. Then we give the return_type. function_name is the name of the function. Then we pass arguments as class_name and object of the class.
Open frnd.cpp	Let us look at an example In this program we will perform addition operation. I have already typed the code on the editor.
Point the cursor frnd.cpp	Note that I have saved the file with the name frnd.cpp Let me explain the code now.
Highlight #include<iostream>	This is our header file iostream.
Highlight using namespace std;	This is the using statement.
Highlight class frnd { private: int a,b; public: void input()	Here we have declared a class frnd. In this we have declared variables a and b as private. And input as public member function.
Highlight cout<<"Enter the value of a and b\n"; cin>>a>>b;	Here we take input from user.
Highlight friend int compute(frnd f1); };	This is our friend function as compute. Here, we have passed arguments as class_name frnd and object of the class. Then we close the class. We can access the private members of class frnd using the friend function
Highlight int compPlease make a mention of the compute method.ute(frnd f1) return int(f1.a+f1.b);	Here we have the compute method, In this we will perform addition operation. Here we add the variables. And return the value. Here we access the private variables in non-member function using the object f1.
Highlight int main() {	This is our main function.
Highlight frnd f; f.input(); cout << "The result is: " << compute(f)<<"\n";	In main function we create an object of class frnd as f. We call the function input. Then we call function compute and pass f as argument. You can see that we have passed the argument as f in function compute. This is done by using the method pass by value. f is passed to the value of f1.
Highlight return 0;	This is the return statement.
Click on Save	Now Click on Save
	Let us execute
Open the terminal Ctrl, Alt and T keys simultaneously	Open the terminal by pressing Ctrl, Alt and T keys simultaneously
Type g++ frnd.cpp -o frnd To execute Type ./frnd	To compile the program type g++ frnd.cpp -o frnd To execute type ./frnd
Highlight Output	Here it is displayed as: Enter the value of a and b I will enter as: 8 4 The output is displayed as: The result is: 12
Please add a little more on the flow of the program.	This brings us to the end of this tutorial.
Slide 7 Summary	In this tutorial we have seen Friend function. eg. friend int compute(frnd f1);
Slide 8 Assignment	As an assignment, Write a program to find out the square and cube of a number.
Slide 9 About the Spoken Tutorial Project	Watch the video available at the link shown It summarizes the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it
Slide 10 Spoken Tutorial Workshops	The Spoken Tutorial Project Team Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to, contact@spoken-tutorial.org
Slide Number 11 Acknowledgement	Spoken Tutorial Project is a part of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro
	This is Ashwini Patil from IIT Bombay signing off Thank You for joining.

Contributors and Content Editors

Ashwini