Difference between revisions of "Advanced-C++/C2/Abstract-Class/English-timed"

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|  The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials.  
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|For more details, please write to, contact@spoken-tutorial.org
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|  Spoken Tutorial Project is a part of the "Talk to a Teacher" project.
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|More information on this Mission is available at the link shown below: [http://spoken-tutorial.org/NMEICT-Intro]
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|More information on this mission is available at the link shown below: http://spoken-tutorial.org/NMEICT-Intro
  
 
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Revision as of 07:28, 29 June 2015


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 version 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 up to 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 file name 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 we are using the 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 hyphen o 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 e.g. class abstractinterface.
04:09 Pure virtual function e.g. 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 classes 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 and 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.

Contributors and Content Editors

Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14

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