Advanced-C++/C2/Abstract-Class/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00.01 | Welcome to the spoken tutorial on abstract class and pure virtual function in C++. |
| 00.08 | In this tutorial we will learn, |
| 00.10 | *Abstract Classes |
| 00.11 | *Pure virtual function |
| 00.13 | *We will do this through an example. |
| 00.16 | To record this tutorial, I am using |
| 00.19 | *Ubuntu OS version 11.10 |
| 00.23 | *g++ compiler v. 4.6.1 |
| 00.27 | Let us start with an introduction to abstract class. |
| 00.31 | Abstract class is always a base class. |
| 00.35 | It contains at least one pure virtual function. |
| 00.39 | We cannot create an instance of abstract class. |
| 00.43 | Let us see pure virtual function. |
| 00.45 | A pure virtual function is a function with no body. |
| 00.49 | It is not defined in the base class. |
| 00.52 | It is declared as: |
| 00.54 | virtual void virtualfunname()=0; |
| 01.00 | A derived class must override the function. |
| 01.04 | Otherwise the compiler will give an error. |
| 01.07 | It is upto a derived class to implement the function. |
| 01.11 | Let us look at an example |
| 01.13 | I have already typed the code on the editor. |
| 01.16 | I will open it. |
| 01.18 | Note that our filename is abstract.cpp |
| 01.22 | This example involves addition and subtraction of two numbers. |
| 01.28 | Let us go through the code. |
| 01.30 | This is our header file as iostream. |
| 01.33 | Here are using std namespace. |
| 01.36 | This is declaration for a class named abstractinterface. |
| 01.41 | Then we have public specifier. |
| 01.44 | In this we have declared a virtual function named "numbers". |
| 01.49 | It is initialized to 0. |
| 01.51 | Then we have a non-virtual function. |
| 01.55 | And two integer variables as a and b. |
| 01.59 | Here we access the input function. |
| 02.01 | In this we accept the numbers a and b. |
| 02.05 | This is a derived class named add. |
| 02.09 | It inherits the properties of the base class "abstractinterface". |
| 02.14 | Here we override the function "numbers". |
| 02.18 | In this we perform addition of two numbers a and b. |
| 02.21 | And store the result in integer variable "sum". |
| 02.25 | Then we print the result. |
| 02.27 | Here we have another derived class as sub. |
| 02.31 | This also inherits the base class "abstractinterface". |
| 02.35 | In this, again, we override the function "numbers". |
| 02.39 | And here we calculate the difference of two numbers a and b. |
| 02.43 | Then we print the difference. |
| 02.45 | This is our main function. |
| 02.48 | Here we create an object of class "add" as obj1. |
| 02.53 | Then we call both the functions "input" and "numbers" using the object obj1. |
| 02.59 | Then we create another object of class "sub" as obj2. |
| 03.04 | Again, we call the two "functions using the object obj2. |
| 03.08 | And this is our return statement. |
| 03.10 | Now let us execute the program. |
| 03.13 | Open the terminal window by pressing Ctrl, Alt and T keys simultaneously on your keyboard. |
| 03.21 | To compile, type:
g++ space abstract dot cpp space hypheno space abs |
| 03.31 | Press Enter |
| 03.32 | Type:
dot slash abs |
| 03.34 | Press Enter |
| 03.36 | It is displayed as
Enter the numbers |
| 03.38 | I will enter as 9 and 4. |
| 03.42 | The output is displayed as Sum is 13 |
| 03.46 | Again we see Enter the numbers. |
| 03.49 | I will enter as 8 and 3. |
| 03.52 | The output is displayed as Diff is 5 |
| 03.56 | This brings us to the end of this tutorial. |
| 03.59 | Come back to our slides. |
| 04.01 | Let us summarize. |
| 04.03 | In this tutorial we learnt, |
| 04.04 | Abstract class eg. class abstractinterface |
| 04.09 | Pure virtual function eg. virtual void numbers()=0; |
| 04.14 | As an assignment
*Create an abstract class student. |
| 04.17 | *Create a pure virtual function as Info |
| 04.20 | *Accept the name and roll no of the student in the function. |
| 04.25 | *Create two derived class marks and sports. |
| 04.29 | *In marks, accept marks of three subjects. |
| 04.32 | *In sports, enter marks scored in sports. |
| 04.35 | *Calculate the total marks. |
| 04.38 | *Then create another derived class as result. |
| 04.41 | *In this, display the name, roll-no, total marks of the student. |
| 04.47 | Watch the video available at the link shown below |
| 04.50 | It summarizes the Spoken Tutorial project |
| 04.53 | If you do not have good bandwidth, you can download and watch it |
| 04.58 | The Spoken Tutorial Project Team Conducts workshops using spoken tutorials |
| 05.03 | Gives certificates to those who pass an online test |
| 05.07 | For more details, please write to, contact@spoken-tutorial.org |
| 05.14 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 05.18 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
| 05.25 | More information on this Mission is available at the link shown below: http://spoken-tutorial.org\NMEICT-Intro |
| 05.30 | This is Ashwini Patil from IIT Bombay signing off
Thank You for watching. |
