Difference between revisions of "C-and-C++/C4/Function-Call/English-timed"
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Revision as of 17:27, 8 March 2017
| 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: |
| 06:58 | Conducts workshops using spoken tutorials. |
| 07:01 | Gives certificates to those who pass an online test. |
| 07:05 | For more details, please write to contact@spoken-tutorial.org. |
| 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
