C++ Operator Overloading

C++ allows operator overloading. Overloaded operators can do operations on predefined data type elements. Overloading allow us to implement polymorphism in C++. Operator overloading means more than one definition of an operator.

There are many operators in C++ like +, -, *, / and so on. But these operators works on built-in data type variable. For example, 

int a=1,b=2,c;

c=a+b;                   //It will works

But these operators do not works on user-defined data types. For example,

object3=object1+object2;         //It will not work

Any operator that works on built-in data types can be overloaded.

C++ operators are:

Arithmetic Operators

Relational Operators

Logical Operators

Bitwise Operators

Assignment Operators

Increment and Decrement Operators

C++ operator overloading syntax:

return type classname :: operator operatorsymbol (list of arguments)

{

        //Function Body

}

How to implement operator overloading?

In c++, operator overloading can be done for class objects. You can implement operator overloading by

1.     Member Function

2.     Non-Member Function

3.     Friend Function

To overload an operator, operator keyword is used.

For example:

class classname

{

        ...

        public:

          returntype operator operatorsymbol (list of arguments)

         {

                //Function Body

         }

        ...

};

C++ operator overloading example:

C++ program to overload + operator

#include<iostream>

using namespace std;

class addobject

{

    int a,b;

public:

    addobject operator + (addobject obj)

    {

        addobject t;

        t.a=a+obj.a;

        t.b=b+obj.b;

        return t;

    }

    void getdata(int x,int y)

    {

        a=x;

        b=y;

    }

    void putdata()

    {

        cout<<"a = "<<a<<endl<<"b = "<<b;

    }

};

int main()

{

    addobject obj1,obj2,obj3;

    obj1.getdata(1,2);

    obj2.getdata(3,4);

    obj3=obj1+obj2;

    obj3.putdata();

    return 0;

}

OUTPUT:

a = 4

b = 6

In this program, you can also also write this statement obj3=obj1+obj2 as obj3=obj1.operator+(obj2).