frnd_function.cpp

#include<iostream>
using namespace std;

class complex{
    int a,b;
    public:
        void setnumber(int n1, int n2){
            a=n1;
            b=n2;
        }

        friend complex sumcomplex(complex o1, complex o2);          //friend function declaration

        void printnumber(){
            cout<<"Your no is "<<a<<"+"<<b<<"i"<<endl;
        }
};
complex sumcomplex(complex o1, complex o2){
    complex o3;
    o3.setnumber((o1.a+o2.a), (o1.b+o2.b));
    return o3;
}

int main(){
    complex c1,c2,sum;
    c1.setnumber(1,2);
    c1.printnumber();

    c2.setnumber(3,4);
    c2.printnumber();

    sum = sumcomplex(c1,c2);
    sum.printnumber();

    return 0;
}