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

Multiple Inheritance.

Hierarchical Inheritnace.

We will do this with the help of examples.

Ubuntu OS version 11.10 and

g++ compiler v. 4.6.1

Point the cursor

multiple.cpp

Now, we will see an example on multiple inheritance.

I have already typed the code on the editor.

I will open it.

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

Let me explain the code.

#include<iostream>

class student

This is the base class.

int roll_no;

char name[20];

These are declared as protected.

class exam_inherit

This is also a base class.

Hence we have two base class here student and exam_inherit.

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

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

class grade:public student, public exam_inherit

{

This inherits the base classes.

Class student and class exam_inherit.

private:

int avg;

public:

void input();

void display();

void average();

int total;

void input_exam();

void display_exam();

input()

display()

average()

input_exam()

and display_exam()

as public functions.

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

void grade::input()

{

cout<<"Enter Roll no:";

cin>>roll_no;

cout<<"Enter Name:";

cin>>name;

}

void grade::display()

{

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

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

}

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;

}

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

void exam::display_exam()

{

total=sub1+sub2+sub3;

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

}

And print the total.

void grade::average()

{

avg=total/3;

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

}

int main()

exam ex;

gd.input();

gd.input_exam();

gd.display();

gd.display_exam();

gd.average();

}

return 0;

Ctrl, Alt and T keys simultaneously

g++ multiple.cpp -o mult

To execute

Type

./mult

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

Type

./mult Press Enter

3

Pratham

67

78

84

Enter Roll no.:

I will enter as 3

Enter Name:

I will enter as Pratham

Enter marks of subject1

I will enter as 67

Enter marks of subject2

I will enter as 78

Enter marks of subject3

I will enter as 84

Output

Roll no is: 3

Name is: Pratham

Total is: 229

Average is: 76

This was multiple inheritance.

Now we will see hierarchical inheritance.

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

I will explain the code now.

protected:

int roll_no;

char name[20];

int sub1;

int sub2;

int sub3;

int total;

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.

class show:public student

{

This is the derived class.

It inherits the properties of class student.

public:

void input();

void display();

};

These are declared as public functions.

void show::input()

{

cout<<"Enter Roll no:";

cin>>roll_no;

cout<<"Enter Name:";

cin>>name;

}

void show::display()

{

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

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

}

class exam:public student

{

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.

public:

void input_exam();

void total_marks();

};

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;

}

It accepts the marks of three subjects.

sub1, sub2 and sub3

void exam::total_marks()

{

total=sub1+sub2+sub3;

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

}

It calculate the total of three subjects.

And print the total.

int main()

{

student st;

show sw;

exam em;

In this we create objects of three classes

as st, sw and ex.

sw.input();

em.input_exam();

sw.display();

em.total_marks();

sw.input();

em.input_exam();

sw.display();

em.total_marks();

return 0;

}

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

g++ hierarchical.cpp -o hier

Type

./hier

Type:

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

Press Enter

Type

./hier

Press Enter

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

Enter marks of subject2

I will enter as 67

Enter marks of subject3

I will enter as 97

Roll no is: 4

Name is: Ashwini

Total is: 251

Come back to our slides.

Summary

In this tutorial, we have seen,

Multiple Inheritance.

Hierarchical Inheritance.

Assignment

Create a class area and perimeter.

Find the area and perimeter of a rectangle.

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