Difference between revisions of "Advanced-C++/C2/Constructor-And-Destructor/English-timed"
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Revision as of 15:26, 3 July 2014
| Time | Narration |
| 00:01 | Welcome to the spoken tutorial on Constructors and Destructors in C++. |
| 00:07 | In this tutorial we will learn, |
| 00:09 | Constructors |
| 00:10 | Types of constructors |
| 00:12 | Destructors. |
| 00:13 | We will do this with the help of some examples. |
| 00:17 | To record this tutorial, I am using |
| 00:20 | Ubuntu Operating System version 11.10, |
| 00:23 | g++ Compiler version 4.6.1. |
| 00:28 | Let us start with an introduction to Constructors. |
| 00:31 | A constructor is a member function. |
| 00:33 | It has the same name as the class name. |
| 00:37 | Constructors cannot return values. |
| 00:40 | It is automatically called when an object is created. |
| 00:44 | Types of Constructors : |
| 00:46 | Parameterized Constructors. |
| 00:49 | Copy Constructors. |
| 00:50 | And Default Constructors. |
| 00:53 | Let us move on to Destructors. |
| 00:56 | Destructors are used to deallocate memory. |
| 00:59 | They are called when an object is destroyed. |
| 01:02 | A destructor takes no arguments and has no return types. |
| 01:07 | Let us see an example on Constructors and Destructors, |
| 01:11 | I have already typed the code on the editor, I will open it. |
| 01:15 | Note that our filename is cons hyphen dest dot cpp |
| 01:20 | In this program we will perform the addition of two numbers using constructor. |
| 01:25 | Let me explain the code now. |
| 01:27 | This is our header file as iostream |
| 01:30 | Here we have used std namespace. |
| 01:33 | Then we have class Addition. a and b are the integer variables. |
| 01:38 | These are the private members of class Addition. |
| 01:42 | Here we have the Public specifier. |
| 01:44 | Then we have the construtor Addition |
| 01:47 | The constructor has the same name as the class name. |
| 01:52 | We have passed two arguements here. |
| 01:54 | Now we have defined a Destructor. |
| 01:57 | For this we use a tilde sign followed by the destructors name. |
| 02:02 | This is a public function add. |
| 02:05 | It returns sum of a and b. |
| 02:08 | Here we access the constructor using the scope resolution operator. |
| 02:12 | a and b are private members. |
| 02:15 | To access the private members we use x and y. |
| 02:19 | Then we access the destructor. |
| 02:21 | In this we print Memory Deallocation. |
| 02:25 | This is our main function. |
| 02:28 | Here we create an object obj of class Addition. |
| 02:32 | Then we pass two arguments as 3 and 4. |
| 02:36 | 3 will be stored in x and 4 will be stored in y. |
| 02:40 | This means a's value is 3 and b'svalue is 4. |
| 02:45 | The constructor that has arguments is called parameterized constructor. |
| 02:50 | Hence this one is the prameterized constructor. |
| 02:53 | Here we call the function add using the object obj. |
| 02:58 | And we print the sum. |
| 03:00 | This is our return statement. |
| 03:02 | Now let us execute the program. |
| 03:05 | Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard. |
| 03:12 | To compile type, g++ space cons hyphen dest dot cpp space hyphen o space cons |
| 03:21 | Press Enter |
| 03:23 | Type dot slash cons |
| 03:25 | Press Enter |
| 03:27 | The output is displayed as |
| 03:29 | Sum is 7 and Memory Deallocation |
| 03:33 | Now let us see an example on Default constructors. |
| 03:37 | Come back ot our program. |
| 03:39 | I have already typed the code. |
| 03:41 | Note that our filename is default dot cpp |
| 03:45 | If a constructor is not declared in the class, |
| 03:48 | Then the compiler assumes a default constructor for the class. |
| 03:53 | Let me explain the code. |
| 03:55 | This is our header file as iostream. |
| 03:58 | Here we have used std namespace. |
| 04:02 | Then we have class Subtraction. |
| 04:04 | Then we have a and b declared as public. |
| 04:08 | Here we have sub function. |
| 04:10 | We have passed two arguments int a and int b. |
| 04:15 | This returns the subtraction of two numbers a and b. |
| 04:19 | This is the defalut constructor. |
| 04:22 | Here we access the default constructor using the scope resolution operator. |
| 04:27 | This is our main function. |
| 04:29 | In this we have defined a variable x. |
| 04:34 | Here we create an object s of class subtraction. |
| 04:39 | Then we call the function sub using the object s. |
| 04:42 | And pass two arguments as 8 and 4. |
| 04:47 | Then the result is stored in variable x. |
| 04:51 | And here we print the difference. |
| 04:54 | This is our return statement. |
| 04:56 | Now let us execute the program. |
| 04:58 | Come back to our terminal. |
| 05:01 | Let us compile type g++ space default dot cpp space hyphen o space def |
| 05:09 | Press Enter |
| 05:10 | Type dot slash def |
| 05:12 | Press Enter |
| 05:14 | The output is return as |
| 05:16 | Difference is 4 |
| 05:18 | Come back to our program. |
| 05:20 | Here you can see that we have passed the arguments within the function. |
| 05:25 | And in our previous example we have passed the arguments within the Object. |
| 05:30 | And here we have passed the arguments using the Object. |
| 05:34 | Now let us go back to our slides. |
| 05:38 | Let us summarize, In this tutorial we learned, |
| 05:41 | Constructors. eg. Addition |
| 05:43 | Parameterized Constructor. eg. Addition obj (3, 4); |
| 05:48 | Destructors eg. ~Addition |
| 05:52 | Default Constructor. eg. Subtraction |
| 05:55 | As an assignment, Create a class named Division. |
| 05:59 | Create a constructor for the class. |
| 06:01 | And Create a function divide which divides two given numbers. |
| 06:06 | Watch the video available at the link shown below |
| 06:09 | It summarises the Spoken Tutorial project. |
| 06:11 | If you do not have good bandwidth, you can download and watch it. |
| 06:16 | The Spoken Tutorial Project Team, Conducts workshops using spoken tutorials . |
| 06:21 | Gives certificates to those who pass an online test . |
| 06:25 | For more details, please write to, |
| 06:27 | contact@spoken hyphen tutorial dot org |
| 06:31 | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
| 06:36 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 06:42 | More information on this Mission is available at the link shown below |
| 06:47 | This is Ashwini Patil from IIT Bombay signing off. Thank You for joining. |
