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

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 now.

#include<iostream>

using namespace std;

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

In this we have passed three arguments.

Then we perform the addition of three numbers.

It is declared as float.

We pass two arguments.

Then we perform the addition of 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.

And 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

To execute type

./ovr

Output

Enter three integers

I will enter as:

10

25

48

The output is displayed as:

Sum of integers is 83

Then we see:

Enter two floating point numbers

I will enter as:

4.5

8.9

Sum of floating point numbers is 13.4

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.

I have already typed the code on the editor.

Lets take a look.

#include <iostream>

using namespace std;

This is our 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 calculate the addition of 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";

}

};

class Multiply: public arithmetic

{

public:

int operations ()

{

mul = a * b;

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

}

};

This also inherits class arithmetic.

In this we calculate the product of two numbers.

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.

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();

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

Then we call function operations.

arith=&subt;

arith->values(42,5);

arith->operations();

Then 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.

Now we call function operations.

arith=&divd;

arith->values(6,3);

arith->operations();

Now we call function operations.

return 0;

}

Now let us execute the program.

g++ override.cpp -o over2

./over2

To execute type:

g++ override.cpp -o over2

./over2

The output

Addition of two numbers is 42

Difference of two numbers is 37

Product of two numbers is 30

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

Function overloading.

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

float add(float, float);

Function Overriding.

eg. virtual int operations ()

int operations ()

Difference between both.

Assignment

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

Using function overloading.

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