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

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Time Narration
00:01 Welcome to the spoken tutorial on friend function in C++.
00:06 In this tutorial we will learn,
00:08 Friend function.
00:10 We will do this with the help of an example.
00:13 To record this tutorial, I am using
00:15 Ubuntu OS v. 11.10
00:19 g++ compiler v. 4.6.1
00:24 Let us start with the introduction to friend function.
00:27 We know, the private data is not accessible outside the class.
00:33 To access the private data we use friend function.
00:37 A friend function is not a member function of the class.
00:42 Friend function can be invoked without using an object.
00:46 The argument passed in the friend function is used as its object.
00:51 Let us see the declaration of a friend function.
00:55 friend keyword is used to declare a friend function.
00:59 Then we give the return_type.
01:02 function_name is the name of the function.
01:05 Then we pass arguments as class_name and object of the class.
01:11 Let us look at an example
01:13 I have already typed the code on the editor.
01:16 I will open it.
01:18 In this program we will perform addition operation.
01:22 Note that our filename is frnd.cpp
01:27 Let me explain the code now.
01:30 This is our header file as iostream.
01:34 Here we are using std namespace.
01:37 Then we have declared a class frnd.
01:41 In this we have declared variables a and b as private.
01:46 Here we have declared a function input as public
01:52 In this we take input from the user.
01:55 This is our friend function as compute.
01:58 Here, we have passed arguments as class_name frnd and object of the class f1.
02:06 Then we close the class.
02:08 Now we can access the private members of class frnd using the friend function.
02:16 Here we have used the compute function.
02:19 In this we will perform addition operation.
02:23 We add the variables a and b
02:26 And then return the value.
02:28 Here we access the private variables in non-member function using the object f1.
02:35 This is our main function.
02:38 In this we create an object of class frnd as f.
02:44 Then we call the function input using the object f.
02:48 And here we call function compute and pass f as argument.
02:54 You can see that we have passed the argument as f in function compute.
02:58 This is done by using the method pass by value.
03:03 f is passed to the value of f1.
03:06 And this is our return statement.
03:09 Now let us execute the program.
03:11 Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard.
03:20 Now type:
03:21 g++ space frnd dot cpp space hyphen o space frnd.Press Enter.
03:32 Type:
dot slash frnd
03:36 Press Enter
03:38 Here it is displayed as: Enter the value of a and b
03:41 I will enter as: 8 and 4
03:46 The output is displayed as:
03:48 The result is: 12
03:51 This brings us to the end of this tutorial.
03:54 Let us move back to our slides.
03:56 Let us summarize:
03:57 In this tutorial we learned
Friend function. eg. friend int compute class name frnd and object f1.
04:08 As an assignment,
Write a program to find out the square and cube of a number.
04:14 Watch the video available at the link shown
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04:51 More information on this Mission is available at the shown below: http://spoken-tutorial.org\NMEICT-Intro
04:56 This is Ashwini Patil from IIT Bombay signing off

Thank You for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14