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 version 11.10
00:19 g++ compiler version 4.6.1
00:24 Let us start with an 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 file-name 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.In this tutorial, we learned Friend function. e.g. 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 below.
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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