C-and-C++/C4/Function-Call/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on Function calls in C and C++.
00:07	In this tutorial, we will learn about type of function calls namely-
00:13	call by value call by reference.
00:16	We will do this through an example.
00:19	To record this tutorial, I am using Ubuntu Operating system version 11.10,
00:26	gcc and g++ Compiler version 4.6.1.
00:31	Let us start with the introduction to function call by value.
00:35	It is a method of passing arguments to the function.
00:40	When we pass a variable by value, it makes a copy of the variable
00:45	before passing to the function.
00:48	Changes made to the arguments, inside the function, will remain in the function.
00:54	It will not be affected outside the function.
00:58	Let us see a program on 'function call by value'.
01:02	I have already typed the program on the editor. I will just open it.
01:08	Please note our file name is callbyval.c.
01:13	In this program, we will calculate the cube of a number. Let me explain the code now.
01:19	This is our header file.
01:21	Here we have function cube having an argument as int x. .
01:27	In this function, we calculate the cube of x and return the value of x.
01:33	This is our main() function.
01:36	Here we give the value of n as 8, 'n' is an integer variable.
01:43	Then we call the function cube.
01:45	And print the value of 'n' and the cube of n.
01:49	And this is our return statement.
01:52	Now let us execute the program.
01:54	open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard.
02:02	To compile , type gcc space callbyval.c space hyphen o space val. Press Enter.
02:12	Now, type ./val (dot slash val). Press Enter.
02:16	The output is displayed as: Cube of 8 is 512.
02:23	Now we will see 'function call by reference'.
02:26	Let us go back to our slides.
02:29	It is another method of passing arguments to the function.
02:33	This method copies the address of the argument instead of the value.
02:39	Changes made to the arguments, inside a function, can affect them outside.
02:45	In this we need to declare the arguments as pointer type.
02:50	Let us see an example on function call by reference.
02:54	Note that our file name is callbyref.c.
02:59	This is our header file as stdio.h.
03:03	Then we have function swap.
03:06	This function will exchange the values of the variables.
03:10	Value of 'a' will be stored in value of 'b' and vice versa.
03:15	You can see that the arguments passed in the function are pointer type.
03:21	Here we have declared an integer variable t.
03:25	First, value of 'a' is stored in 't'.
03:28	Then value of 'b' is stored in 'a'.
03:32	And then value of 't' is stored in 'b'.
03:37	Like this, the values are exchanged.
03:40	This is our main() function.
03:42	Here we have declared two integer variables as i and j.
03:49	Then we take the values of i and j as user inputs.
03:53	Ampersand i (&i) and Ampersand j (&j) will give the memory address of i and j.
03:59	First, we print the values before swapping.
04:04	Then we call the function swap.
04:06	And then we print the values after swapping.
04:10	And this is our return statement.
04:13	Now let us execute the program.
04:16	Switch back to our terminal.
04:19	To compile type gcc space callbyref dot c space hyphen o space ref. Press Enter.
04:29	Now type dot slash ref. Press Enter.
04:33	We see, 'Enter the values'. I will enter as 6 and 4.
04:40	The output is displayed as: Before swapping 6 and 4
04:44	After swapping 4 and 6.
04:48	Now let us see how to execute the same program in C++.
04:53	I have the code, lets go through it.
04:57	This is the second program, function call by reference .
05:01	Note that our file name is callbyref.cpp
05:06	Let us go through the code.
05:08	This is our header file as iostream .
05:12	Here we are using the std namespace.
05:16	The function declaration is same in C++.
05:19	In this we pass the arguments as ampersand x and ampersand y.
05:25	This will give the memory address of x and y.
05:29	Then we swap the values.
05:32	Rest of the code is similar to our C code.
05:36	The printf statement is replaced by cout and the scanf statement is replaced by cin.
05:44	Now let us execute the program. Come back to our terminal.
05:48	To compile type, g++ space callbyref.cpp space hyphen o space ref1, press Enter.
06:00	Now, type dot slash ref1. Press Enter.
06:05	Here it is displayed as:
06:07	Enter values of a and b
06:10	I will enter as 4 and 3.
06:13	The output is displayed.
06:15	Before swapping a and b 4 and 3
06:19	After swapping a and b 3 and 4
06:23	This brings us to the end of this tutorial.
06:26	Let us go back to our slides.
06:30	Let us summarize, In this tutorial we learnt:
06:32	Function call by value.
06:34	And Function call by reference.
06:37	As an assignment,write a similar program to calculate the cube of a number,
06:42	using call by value in C++.
06:46	Watch the video available at the link shown below.
06:49	It summarizes the Spoken Tutorial project.
06:52	If you do not have good bandwidth, you can download and watch it.
06:56	The Spoken Tutorial Project Team:
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07:11	Spoken Tutorial Project is a part of the Talk to a Teacher project.
07:15	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
07:23	More information on this mission is available at the link shown below.
07:27	This is Ashwini Patil from IIT Bombay, signing off.
07:31	Thank You for joining.

Contributors and Content Editors

Kavita salve, Krupali, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha