Difference between revisions of "C-and-C++/C4/Function-Call/English-timed"
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Revision as of 11:39, 17 October 2013
| Time' | Narration |
| 00:02 | Welcome to the spoken tutorial on Function call in C and C++ |
| 00:08 | In this tutorial we will learn about type of function calls namely, call by value. |
| 00:15 | call by reference. |
| 00:17 | We will do this through an example. |
| 00:20 | To record this tutorial, I am usingUbuntu Operating system version 11.10gcc and g++ Compiler version 4.6.1 |
| 00:32 | Let us start with the introduction to functions call by value |
| 00:37 | 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. |
| 00:46 | Before passing to the function. |
| 00:49 | Changes made to the arguments inside the function will remain in the function. |
| 00:55 | It will not be affected outside the function. |
| 00:59 | 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 filename is callbyval.c.
|
| 01:13 | In this program we will calculate the cube of a number. Let me explain the code now. |
| 01:20 | This is our header file |
| 01:22 | Here we have function cube having an argument as int x. |
| 01:28 | In this function we calculate the cube of x and return the value of x. |
| 01:34 | This is our main function. |
| 01:37 | Here we give the value of n as 8. n is an integer variable |
| 01:44 | Then we call the function cube. |
| 01:46 | And print the value of n and the cube of n. |
| 01:50 | And This is our return statement. |
| 01:53 | Now let us execute the program.
|
| 01:55 | open the terminal window by pressing ' Ctrl, Alt and T keys simultaneously on your keyboard. |
| 02:03 | To compile , type |
| 02:04 | gcc callbyval.c -o val. Press Enter |
| 02:13 | Now type ./val.Press Enter |
| 02:17 | The output is displayed as Cube of 8 is 512. |
| 02:23 | Now we will see function call by reference. |
| 02:27 | Let us go back to our slides. |
| 02:29 | It is another method of passing arguments to the function. |
| 02:34 | This method copies the address of the argument instead of the value. |
| 02:40 | Changes made to the arguments inside a function can affect them outside. |
| 02:46 | In this we need to declare the arguments as pointer type. |
| 02:51 | Let us see an example on function call by reference. |
| 02:55 | Note that our filename is callbyref.c
|
| 02:59 | This is our headerfile as stdio.h |
| 03:03 | Then we have function swap
|
| 03:06 | This function will exchange the values of the variables.
|
| 03:11 | Value of *a will be stored in value of *b and vice-versa. |
| 03:16 | You can see that the arguments passed in the function are pointer type. |
| 03:22 | Here we have declared an integer variable t. |
| 03:25 | First value of *a is stored in t. |
| 03:29 | Then value of *b is stored in *a. |
| 03:33 | And Then value of t is stored in *b . |
| 03:37 | Like this the values are exchanged. |
| 03:40 | This is our main function. |
| 03:43 | 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. |
| 03:54 | &i and &j will give the memory address of i and j. |
| 04:00 | First we print the values before swapping. |
| 04:05 | Then we call the function swap |
| 04:07 | And then we print the values after swapping. |
| 04:11 | And This is our return statement. |
| 04:14 | Now let us execute the program |
| 04:17 | Switch back to our terminal |
| 04:19 | To compile type |
| 04:22 | gcc callbyref.c -o ref. Press Enter |
| 04:30 | Now type ./ref. Press Enter
|
| 04:34 | We see, enter the values I will enter as 6 and 4 |
| 04:40 | The output is displayed as,before swapping 6 and 4 |
| 04:45 | 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. |
| 04:58 | This is the second program function callbyreference . |
| 05:02 | Note that our filename is callbyref.cpp |
| 05:07 | Let us go through the code now |
| 05:09 | This is ou header file as iostream
|
| 05:13 | Here we are using the std namespace |
| 05:16 | The function declaration is same in C++. |
| 05:20 | In this we pass the arguments as &x and &y. |
| 05:25 | This will give the memory address of x and y. |
| 05:30 | Then we swap the values. |
| 05:33 | Rest of the code is similar to our C code. |
| 05:37 | 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 |
| 05:49 | To compile type; g++callbyref.cpp -o ref1 press Enter |
| 06:01 | Now Type ./ref1, Press Enter |
| 06:06 | Here it is displayed as: |
| 06:07 | Enter values of a and b |
| 06:10 | I will enter as 4 and 3 |
| 06:14 | The output is displayed |
| 06:16 | Before swapping a and b: 4 and 3 |
| 06:20 | After swapping a and b: 3 and 4 |
| 06:24 | This brings us to the end of this tutorial. |
| 06:27 | Let us go back to our slides. |
| 06:30 | Let us summarize, In this tutorial we learn't: |
| 06:33 | Function call by value. |
| 06:35 | And Function call by reference. |
| 06:38 | As an assignment |
| 06:39 | Write a similar program to calculate the cube of a number. |
| 06:43 | Using call by value in C++. |
| 06:47 | Watch the video available at the link shown below ,http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial |
| 06:50 | It summarises the Spoken Tutorial project |
| 06:53 | If you do not have good bandwidth, you can download and watch it |
| 06:57 | The Spoken Tutorial Project Team |
| 06:59 | Conducts workshops using spoken tutorials |
| 07:02 | Gives certificates to those who pass an online test |
| 07:05 | For more details, please write to contact@spoken-tutorial.org |
| 07:12 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 07:16 | 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: http://spoken-tutorial.org\NMEICT-Intro |
| 07:27 | This is Ashwini Patil from IIT Bombay. Signing off.
Thank You for joining |
Contributors and Content Editors
Kavita salve, Krupali, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha
