Difference between revisions of "Advanced-C++/C2/Inheritance/English"

Inheritance.

Types of inheritance.

We will do this with the help of examples.

Ubuntu OS version 11.10

g++ compiler v. 4.6.1

When one object acquires the property of another it is called as inheritance.

It is the process of reusing the existing class without modifying them.

Single level inheritance

Multiple level inheritance

Hierarchical Inheritance

Multilevel inheritance

Hybrid Inheritance

The base class has its own properties and functionality.

It is also called as parent class.

It has the common qualities that all the objects can inherit.

The derived class is the child class.

Derived class inherits the properties and functionality of the base class.

Let us see what is single level inheritance.

In single level inheritance only one base class and one derived class is needed.

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

In Multilevel inheritance the subclass acts as the base class for other classes.

Point the cursor

exam_inherit.cpp

I have already typed the code on the editor.

I will explain it.

Note that I have saved the file with the name exam_inherit.cpp

#include <iostream>

using std namespace

class student

int width;

int height;

As private members of class student.

public:

void input();

void display();

};

void student :: input()

{

cout << “Enter Roll no.”;

cin>>roll_no;

cout<<"Enter Name:";

cin>>name;

}

void student::display()

class exam:public student

{

This is the derived class.

It inherits the the data and function of class student.

private:

int msub1;

int msub2;

int msub3;

int total;

As private variables of class exam_inherit.

public:

void input_exam();

void display_exam();

};

Here we close the class.

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;

}

void exam::display_exam()

{

total=sub1+sub2+sub3;

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

}

Then we print the total.

int main()

exam ex;

ex.input();

ex.input_exam();

ex.display();

ex.display_exam();

return 0;

}

return 0;

Ctrl, Alt and T keys simultaneously

g++ exam_inherit.cpp -o exam

To execute

Type

./exam

g++ exam_inherit.cpp (space)-o (space) exam

To execute

Type

./exam

Output

Enter Roll no.:

I will enter as 1

Enter Name:

I will enter as Arya

Enter marks of subject1

I will enter as 60

Enter marks of subject1

I will enter as 70

Enter marks of subject1

I will enter as 80

Output

Roll no is: 1

Name is: Arya

Total is: 210

multilevel.cpp

Let us switch back to our ediotr.

Note that our filename is multilevel.cpp

int total;

As public variable of class exam_inheri.

This is because the private members are not accessed by the derived class.

class grade:public exam_inherit

{

This inherits the class exam_inherit.

Class grade is the derived class

And class exam_inherit is the base class for class grade.

private:

int avg;

public:

void average();

};

And function average as public function.

Then we close the class.

void grade::average()

{

avg=total/3;

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

}

Then we print the average.

int main()

{

grade gd;

gd.input();

gd.input_exam();

gd.display();

gd.display_exam();

gd.average();

Then we call all the functions usign gd.

gd.input()

input_exam

display

display_exam

and the average function.

return 0;

And exam_inherit is the base class for grade.

And class student is the base class for class exam_inherit.

Come back to our terminal.

g++ multilevel.cpp -o multilevel

Type

./multilevel

g++ multilevel.cpp -o mul

Press Enter

Type

./multilevel

Press Enter

Type:

2

Pratham

65

67

82

Enter Roll no.:

I will enter as 2

Enter Name:

I will enter as Pratham

Enter marks of subject1

I will enter as 65

Enter marks of subject1

I will enter as 67

Enter marks of subject1

I will enter as 82

Output

Roll no is: 2

Name is: Pratham

Total is: 214

Average is: 71

Let us come back to the slides

Summary

In this tutorial, we have seen,

Inheritance.

Types of inheritance.

Assignment

Create a class Shape.

Create two functions of the class as Area and Perimeter.

Find the area and perimeter of various shapes like square, rectangle and circle.

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