08_oops.cpp

#include<iostream>
using namespace std;
//forwaord declaration
class complex;

class calculator {
    public:
    int add(int a , int b){     
        return (a + b);
    }
int sumRealComplex(complex, complex);
int sumComComplex(complex, complex);
  };

class complex {
  int a,b; 
// individual declaring function as friend

  // ** friend int calculator ::sumRealComplex(complex ,complex );
   //**  friend int calculator ::sumComComplex(complex ,complex );

//Aliter : declearing the entire calculator class as friend.
friend  class calculator;
public:
void setNumber(int n1 , int n2) {     //1
  a=n1;
  b=n2;
}
void printNumber(){
cout<< "your number is "<<a<<" + "<<b<<"i"<<endl;
}
};
int calculator::sumRealComplex(complex o1,complex o2){
        return (o1.a + o2.a);
    }
    int calculator::sumComComplex(complex o1,complex o2){
        return (o1.b + o2.b);
    }
int main(){
    complex o1,o2;
    o1.setNumber(1,4);
      o2.setNumber(5,7);
      calculator calc;
      int res = calc.sumRealComplex(o1,o2);
      cout<<"the sum of real part of o1 and o2 is"<<res<<endl;
        int resc = calc.sumComComplex(o1,o2);
      cout<<"the sum of com part of o1 and o2 is"<<resc<<endl;
    return 0;
}