Question

Hi I am trying to do operator overloading for +(addition) operator to add my user defined datatype objects .
Following is the code for that.

  #include <iostream>
using namespace std;
class complex {
    int i;
    double f;
public:
    complex(int ii=0,double ff=0){
        i = ii;
        f = ff;
    }
    complex operator+(complex object) {
        complex result;
        result.i = this->i + object.i;
        result.f = this->f + object.f;
        return result;
    }
    void display() {
        cout << i <<"\t"<< f;
        cout << endl;
    }
};
int main(){
    complex obj1(1,1.1),obj2(2,2.2),obj3;
    int i(5);
    obj3 = obj1 + obj2;
    obj3.display();
    obj3 = obj3 + i;
    obj3.display();
    obj3 = i + obj3;//generates me compiler error
    obj3.display();
    return 0;
}

I have learnt that when I do obj1 + obj2,it is expanded by the compiler as obj1.operator+(obj2);
So that part of code works fine.

But when I do add an int and complex ,I think it get expanded as i.operator(obj1).

So it gives me compiler errors.

Should I define operator+ function in int class or how to solve this?
Please suggest,
Thank you,

Answer 1

You will have to provide an overloaded version of + which takes int and class complex object as input parameters. This function should be a non member function.

complex operator+(int i, complex object) 

Note that additionally, if you want to access protected or private members inside this overloaded function then it will have to be made friend of your complex class.

This is a peculiar example of the strength of free functions used for operator overloading as against member function operator overloads.