Difference between revisions of "Advanced-C++/C2/Polymorphism/English-timed"
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Revision as of 17:16, 9 July 2014
Time | Narration |
00:02 | Welcome to the spoken tutorial on Polymorphism in C++. |
00:07 | In this tutorial we will learn, |
00:10 | Polymorphism. |
00:11 | Virtual members. |
00:13 | We will do this through an example. |
00:16 | To record this tutorial, I am using Ubuntu OS version 11.10 gcc g++ compiler v. 4.6.1 |
00:27 | Let us start with the introduction to polymorphism. |
00:31 | Polymorphism is the ability to take different forms. |
00:36 | It is the mechanism to use a function with same name in different ways. |
00:42 | Let us see virtual functions. |
00:45 | Virtual function is the member function of a class. |
00:49 | It can be overriden in its derived class. |
00:53 | It is declared with virtual keyword. |
00:57 | Virtual function call is resolved at run-time. |
01:01 | Now let us see an example on virtual functions. |
01:06 | I have already written the code. |
01:08 | Let us go through it. |
01:10 | Note that our filename is virtual.cpp |
01:15 | In this program: |
01:16 | We will calculate the area of a rectangle, parallelogram and traingle. |
01:22 | This is our header file as iostream. |
01:25 | Here we are using std namespace. |
01:29 | Then we have a class parallelogram |
01:33 | This is the base class. |
01:35 | In this we have declared integer variables as width, height and ar. |
01:42 | These are declared protected. |
01:45 | Then we have function set_values declared as public. |
01:50 | Here we have passed two arguments as a and b. |
01:55 | Then we access the protected members using the public members. |
02:00 | This is our virtual function area. |
02:04 | Here we calculate the area of parallelogram. |
02:07 | Then we have class Rectangle as derived class. |
02:12 | It inherits the properties of base class parallelogram. |
02:17 | Here we override the function area. |
02:21 | Then we calculate the area of the rectangle. |
02:23 | And print the value. |
02:25 | Here we have another derived class as triangle. |
02:29 | This also inherits properties of the base class parallelogram. |
02:35 | Here again we override the function area. |
02:39 | Then we calculate the area of the triangle. |
02:41 | And print the value. |
02:43 | This is our main function. |
02:46 | Here we create an object of class parallelogram as p. |
02:52 | We can see here pointer parallel. |
02:56 | This is the pointer of class parallelogram. |
03:00 | This is called as Base pointer. |
03:03 | Pointer of base class can point to the object of the derived class. |
03:08 | Here we create objects of class Rectangle and Triangle. |
03:14 | Here, Parallel is assigned to the address of p. |
03:18 | Then we pass arguments as 3 and 2. |
03:23 | Then we call function area. |
03:26 | Here, Parallel is assigned to the address of rect |
03:30 | rect is the object of class Rectangle. |
03:33 | Again we pass arguments as 4 and 5. |
03:37 | And we call the function area. |
03:40 | And at last we assign Parallel is assigned to the address of Triangle |
03:45 | trgl. |
03:47 | This is the object of class Triangle. |
03:51 | Here we pass arguments as 6 and 5. |
03:54 | And call function area. |
03:56 | This is our return statement |
03:59 | Now let us execute the program |
04:02 | open the terminal by pressing Ctrl, Alt and T keys simultaneously on your keyboard. |
04:09 | To compile type: |
04:10 | g++ virtual.cpp -o vir Press Enter |
04:20 | Type: ./vir Press Enter |
04:24 | We can see that, The output is displayed as: |
04:27 | Area of parallelogram is 6 |
04:29 | Area of rectangle is 20 |
04:31 | and Area of triangle is 15 |
04:34 | Come back to our slides. |
04:36 | Let us summarize. |
04:37 | In this tutorial, we learnt |
04:39 | Polymorphism. |
04:41 | Virtual functione.g. Virtualint area |
04:45 | As an assignment |
04:46 | Calculate the perimeter of rectangle, square and triangle. |
04:50 | Create perimeter as a virtual function. |
04:54 | Watch the video available at the link shown below |
04:57 | It summarizes the Spoken Tutorial project |
05:00 | If you do not have good bandwidth, you can download and watch it |
05:04 | The Spoken Tutorial Project Team |
05:06 | Conducts workshops using spoken tutorials |
05:09 | Gives certificates to those who pass an online test |
05:14 | For more details, please write to, contact@spoken-tutorial.org |
05:21 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
05:25 | It is supported by the National Mission on Education through ICT, MHRD, Government of Indiaabout:startpage |
05:32 | More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro |
05:37 | This is Ashwini Patil from IIT Bombay signing off
Thank You for joining. |