Difference between revisions of "Advanced-C++/C2/Function-Overloading-And-Overriding/English"

Function Overloading.

Function Overriding.

We will do this with the help of examples.

Ubuntu OS version 11.10

g++ compiler v. 4.6.1

Function Overloading means two or more functions can have same name.

The number of arguments and the data-type of the arguments will be different.

When a function is called it is selected based on the argument list.

In this program we will perform addition operation.

I have already typed the code on the editor.

overload.cpp

Let me explain the code.

#include<iostream>

using namespace std;

int add(int a, int b, int c)

Please write the function.

In this we have passed three arguments.

Int a, int b and int c;

Then we perform addition of three numbers.

And we return the value.

float add(float d, float e)

{

return (d + e);

}Pls indicate the text to be highlighted.

It is declared as float.

We pass two arguments.

Then we perform the addition operation on two numbers.

int main()

{

int add(int, int, int);

float add(float, float);

int a,b,c;

float d,e,sum;

Then we declare the variables.

cout << "Enter three integers\n";

cin >> a >> b >>c;

sum = add(a, b, c);

cout << "Sum of integers: " << sum << "\n";

Then we call the function add with three arguments.

And store the result in variable sum.

Here we print the result.

cout << "Enter two floating point numbers\n";

cin >> d >> e;

sum = add(d, e);

cout << "Sum of floats: " << sum << "\n";

The result is stored in sum.

And we print the result.

return 0;

Ctrl, Alt and Tkeys simultaneously

g++ overload.cpp -o ovr

To execute

Type

./ovr

g++ overload.cpp -o ovr

Press Enter

To execute type

./ovr

Press Enter

Output

Enter three integers

I will enter as:

10

25

48

The output is displayed as:

Sum of integers is 83

Now we see:

Enter two floating point numbers

I will enter as:

4.5

8.9

The output is displayed as:

Sum of floating point numbers is 13.4

Let us switch back to our slides.

Redefining a base class function in the derived class.

The derived class function overrides the base class function.

But the arguments passed are same.

And the return-type is also same.

Here is an example on function Overriding

Note that our filename is override.cpp.

Let us go through the code.

#include <iostream>

using namespace std;

Here we have the std namespace.

class arithmetic

{

protected:

int a, b, sum, sub, mul, div;

In this we have declared integer variables as protected.

public:

void values (int x, int y)

{

a=x, b=y;

}

virtual int operations ()

{

sum= a + b;

cout<< "Addition of two numbers is "<< sum<<"\n";

}

};

In this we add the two numbers.

And print the sum.

Here we close the class.

class Subtract: public arithmetic

{

This inherits the base class arithmetic.

public:

int operations ()

{

sub= a - b;

cout<< "Difference of two numbers is "<<sub <<"\n";

}

};

And we print the difference.

class Multiply: public arithmetic

{

public:

int operations ()

{

mul = a * b;

cout<< "Product of two numbers is "<< mul<<"\n";

}

};

This also inherits base class arithmetic.

In this we calculate the product of two numbers.

And display the product.

class Divide: public arithmetic

{

public:

int operations ()

{

div = a / b;

cout<< "Division of two numbers is "<< div<<"\n";

}

};

In this we calculate the division of two numbers.

And then we display the division.

int main()

{

arithmetic *arith, p;

Subtract subt;

Multiply mult;

Divide divd;

In this we create an object of class arithmetic as p.

arith is the pointer to the class arithmetic.

Then we have subt object of class Subtract.

mult object of class Multiply.

And divd object of class Divide.

arith=&p;

arith->values(30,12);

arith->operations();

Reply to Rahul Katarey (15/03/2013, 16:33): "..."

P is set to the address of parallel.

Here we pass arguments as 30 and 12 in function values.

Then we call the function operations.

arith=&subt;

arith->values(42,5);

arith->operations();

And we pass 42 and 5 as arguments.

Again we call function operations.

arith=&mult;

arith->values(6,5);

arith->operations();

And pass arguments as 6 and 5.

Then we call function operations.

arith=&divd;

arith->values(6,3);

arith->operations();

Then we call function operations.

return 0;

}

Let us execute the program.

g++ override.cpp -o over2

./over2

To execute type:

g++ override.cpp -o over2

Press Enter

Type:

./over2

Press Enter

The output

Addition of two numbers is 42

Difference of two numbers is 37

Product of two numbers is 30 and

Division of two numbers is 2

Overloading can occurs without inheritance.

Overriding occurs when one class is inherited from another.

In overloading the arguments and the return-type must differ.

In overriding the arguments and the return type must be same.

In overloading the function name is same.

But it behaves differently depending on the arguments passed to them.

In overriding the function name, arguments passed and the return type is same.

Derived class function can perform different operations from the base class.

Summary

In this tutorial we have seen

Function overloading.

eg. int add(int, int, int);

We have passed three arguments.

float add(float, float);

Here we have passed two arguments.

Function Overriding.

eg. virtual int operations ()

int operations ()

that was overrided.

And then we saw,

Difference between both.

Assignment

Write a program that will calculate the area of rectangle, square and circle.

Using function overloading.

About the Spoken Tutorial Project

It summarizes the Spoken Tutorial project

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

Spoken Tutorial Workshops

Conducts workshops using spoken tutorials

Gives certificates to those who pass an online test

For more details, please write to,

contact@spoken-tutorial.org

Acknowledgement

It is supported by the National Mission on Education through ICT, MHRD, Government of India

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

Thank You for joining.