Advanced-C++/C2/More-On-Inheritance/English

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Title of script: Multiple and Hierarchical Inheritance in C++

Author: Ashwini Patil

Keywords: Multiple Inheritance, Hierarchical Inheritance, Video tutorial.


Visual Cue
Narration
Slide 1 Welcome to the spoken tutorial on Multiple and Hierarchical Inheritance in C++.
Slide 2 In this tutorial we will learn,
  • Multiple Inheritance.
  • Hierarchical Inheritance.
  • We will do this with the help of examples.
Slide 3 To record this tutorial, I am using,
  • Ubuntu OS version 11.10 and
  • g++ compiler v. 4.6.1
Open multiple.cpp


Point the cursor

multiple.cpp

In multiple inheritance, derived class inherits from more than one base class.

Now, we will see an example on multiple inheritance.

I have already typed the code on the editor.

I will open it.

Note that our filename is multiple.cpp

In this program we will display the name, roll no, marks and average of the student.

Let me explain the code.

Highlight

#include<iostream>

This is our headerfile as iostream
Highlight


Here we are using std namespace
Highlight

class student


Then we have class "student".

This is the base class.

Highlight

int roll_no;

char name[20];

In this we have roll_no as integer variable and name as character variable.

These are declared as protected.

Highlight

class exam_inherit

Then we have another class "exam_inherit"

This is also a base class.

Hence we have two base class here- student and exam_inherit.

In this we have 3 variables- sub1, sub2, sub3 as protected.

This is because protected variables can be accessed by derived class.

Highlight

class grade:public student, public exam_inherit

{

Now here we have class "grade" which is the derived class.

This inherits the base classes - class "student" and class "exam_inherit".

Highlight

private:

int avg;

In this we have avg as integer variable declared as private.
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public:

void input();

void display();

void average();

int total;

void input_exam();

void display_exam();


Then we have function

input()

display()

average()

input_exam()

and display_exam()

as public functions.

In this we have "total" as integer variable declared as public.

Highlight

void grade::input()

{

cout<<"Enter Roll no:";

cin>>roll_no;

cout<<"Enter Name:";

cin>>name;

}

Then we use input function to accept the roll_no and name of the student.
Highlight

void grade::display()

{

cout<<"Roll no is:"<<roll_no<<"\n";

cout<<"Name is:"<<name <<"\n";

}

In display function, we display the roll_no and name of the student.
Highlight

void grade::input_exam()

{

cout<<"Enter marks of subject1:";

cin>>sub1;

cout<<"Enter marks of subject2:";

cin>>sub2;

cout<<"Enter marks of subject3:";

cin>>sub3;

}

Here we have function input_exam.

In this we accept the marks of three subjects as sub1, sub2 and sub3.

Highlight

void exam::display_exam()

{

total=sub1+sub2+sub3;

cout<<"Total is :" <<total<<"\n";

}

Then in display_exam function, we calculate the total of three subjects.

And print the total.

Highlight

void grade::average()

{

avg=total/3;

cout<<"Average is :"<<avg<<"\n";

}

And in function average we calculate the average.
Highlight

int main()

This is our main function.
Highlight

exam ex;

In this we create an object of class grade which is the derived class as gd.
Highlight

gd.input();

gd.input_exam();

gd.display();

gd.display_exam();

gd.average();

}

Then we call all the above functions
Highlight

return 0;

This is the return statement.
Now let us execute the program
Open the terminal by pressing Ctrl, Alt and T keys simultaneously Open the terminal window by pressing Ctrl, Alt and T keys simultaneously, on your keyboard.
Type

g++ multiple.cpp -o mult

To execute

Type

./mult

To compile, type

g++ space multiple.cpp space -o space mult Press Enter


Type

./mult Press Enter

Type:

3

Pratham

67

78

84

Here we see, Enter Roll no.:

I will enter as 3

Enter Name:

I will enter as Pratham

Enter marks of subject1

I will enter as 67

subject2 as 78

subject3 as 84

Highlight

Output

The output is displayed as

Roll no is: 3

Name is: Pratham

Total is: 229

Average is: 76

This was multiple inheritance.

Now we will see hierarchical inheritance.

Come back to our program.

In hierarchical inheritance multiple derived classes inherits from one base class.

Open file hierarchical.cpp Note that our filename is hierarchical.cpp

I will explain the code now.

This is our header file as iostream.
Here we have used the std namespace
Highlight

protected:

int roll_no;

char name[20];

int sub1;

int sub2;

int sub3;

int total;

Then we have class 'student' which is the base class.

In this, we have roll_no as integer variable.

Sub1, sub2, sub3 and total as integer variables.

Then name as character variable.

These are declared protected.

Highlight

class show:public student

{

Here we have another class 'show'.

This is the derived class.

It inherits the properties of class student.


Highlight

public:

void input();

void display();

};

In this we have two functions: "input" and "display".

These are declared as public functions.

Highlight

void show::input()

{

cout<<"Enter Roll no:";

cin>>roll_no;

cout<<"Enter Name:";

cin>>name;

}

In function input we accept the roll_no and name of the student.
Highlight

void show::display()

{

cout<<"Roll no is:"<<roll_no<<"\n";

cout<<"Name is:"<<name <<"\n";

}

In function display we display the roll_no and name of the student.
Highlight

class exam:public student

{

Then we have another derived class as class exam.

This also inherits class student.

We can see that there are two derived class- class exam and class show.

Both the classes inherits the class "student".

Highlight

public:

void input_exam();

void total_marks();

};

In class exam we have two functions as "input_exam" and "total marks" declared as public.
Highlight

void exam::input_exam()

{

cout<<"Enter marks of subject1:";

cin>>sub1;

cout<<"Enter marks of subject2:";

cin>>sub2;

cout<<"Enter marks of subject3:";

cin>>sub3;

}

Here we access the function "input_exam"

It accepts the marks of three subjects- sub1, sub2 and sub3

Highlight

void exam::total_marks()

{

total=sub1+sub2+sub3;

cout<<"Total is :" <<total<<"\n";

}

Then we have "total_marks" function.

It calculates the total of three subjects and print the total.

Highlight

int main()

{

student st;

show sw;

exam em;

This is our main function.

In this we create objects of three classes

as st, sw and ex.

Highlight

sw.input();

em.input_exam();

sw.display();

em.total_marks();

Then we call all the above functions.

sw.input();

em.input_exam();

sw.display();

em.total_marks();

Highlight

return 0;

}

And this is our return statement.
On the terminal Now let us execute the program.

Come back to the terminal. Let me clear the prompt.

Type

g++ hierarchical.cpp -o hier

Type

./hier

Let us compile.

Type:

g++ space hierarchical.cpp space-o space hier

Press Enter

Type

./hier

Press Enter

On the terminal

Type:

4

Ashwini

87

67

97

Enter Roll no.:

I will enter as 4

Enter Name:

I will enter as Ashwini

Enter marks of subject1

I will enter as 87

subject2 as 67 and subject3 as 97

On the terminal The output is displayed as

Roll no is: 4

Name is: Ashwini

Total is: 251

Switch back to the slides This brings us to the end of this tutorial.

Come back to our slides.

Slide 7

Summary

Let us summarize

In this tutorial, we learnt,

  • Multiple Inheritance.
  • Hierarchical Inheritance.
Slide 6

Assignment

As an assignment

Create a class area and perimeter.

Find the area and perimeter of a rectangle.

Slide 8

About the Spoken Tutorial Project

Watch the video available at the link shown

It summarizes the Spoken Tutorial project

If you do not have good bandwidth, you can download and watch it

Slide 9

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Slide Number 10


Acknowledgement

Spoken Tutorial Project is a part of the Talk to a Teacher project

It is supported by the National Mission on Education through ICT, MHRD, Government of Indiaabout:startpage

More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro

This is Ashwini Patil from IIT Bombay signing off

Thank You for joining.

Contributors and Content Editors

Ashwini, Nancyvarkey

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