Operator Overloading

struct USCurrency 

{

    int dollars;

    int cents;

};

USCurrency a = {2, 50};

USCurrency b = {1, 75};

USCurrency c = a + b;     //Error

struct USCurrency 

{

    int dollars;

    int cents;

};

USCurrency a = {2, 50};

cout << a;                         //Error

How to make operators work for user defined data types?

Operator Overloading

Operator overloading can be done by implementing a function which can be :

Member Function

Non-Member Function

Friend Function

Restrictions on Operator Overloading

• Precedence and Associativity of an operator cannot be changed.

• Arity (numbers of Operands) cannot be changed. Unary operator remains unary, binary remains binary etc.

• No new operators can be created, only existing operators can be overloaded.

• Cannot redefine the meaning of a procedure. You cannot change how integers are added.

#include <iostream>

using namespace std;

struct USCurrency 

{

    int dollars;

    int cents;

};

USCurrency operator+(const USCurrency m, const USCurrency o) 

{

     USCurrency tmp = {0, 0};

     tmp.cents = m.cents + o.cents;

     tmp.dollars = m.dollars + o.dollars;

     if(tmp.cents >= 100) 

     {

         tmp.dollars += 1;

         tmp.cents -= 100;

     }

     return tmp;

}

ostream& operator<<(ostream &output, const USCurrency &o)

{

    output << "$" << o.dollars << "." << o.cents;

    return output;

}

int main() 

{

    USCurrency a = {2, 50};

    USCurrency b = {1, 75};

    USCurrency c = a + b;

    cout << c << endl;

    return 0;

}

#include <iostream>

using namespace std;

struct USCurrency 

{

        int dollars;

        int cents;

        USCurrency operator+(const USCurrency o) 

        {

            USCurrency tmp = {0, 0};

            tmp.cents = cents + o.cents;

            tmp.dollars = dollars + o.dollars;

            if(tmp.cents >= 100) 

            {

                tmp.dollars += 1;

                tmp.cents -= 100;

            }

            return tmp;

        }

ostream& operator<<(ostream &output)

        {

            output << "$" << dollars << "." << cents;

            return output;

        }

};

int main() 

{

    USCurrency a = {2, 50};

    USCurrency b = {1, 75};

    USCurrency c = a + b;

    return 0;

}