Can't access private members of a class despite friend class - c++

Question

I am doing a homework assignment on overloading operators. This is my code:
#include<iostream>
#include<cmath>
using namespace std;
class ComplexNumber{
double real;
double imaginary;
public:
friend class Equation;
};
class Equation{
ComplexNumber *broevi;
char *znaci;
int n;
public:
Equation(){
broevi=new ComplexNumber[0];
znaci=new char[0];
n=0;
}
friend istream &operator >>(istream &in, Equation &e){
int k=1;
while(k){
char *tmp; ComplexNumber *b;
tmp=new char[e.n+1];
for(int i=0; i<e.n; i++)
tmp[i]=e.znaci[i];
b=new ComplexNumber[e.n+1];
for(int i=0; i<e.n; i++)
b[i]=e.broevi[i];
in>>e.broevi[e.n].real>>e.broevi[e.n].imaginary;
in>>tmp[e.n];
if(tmp[e.n]=='=')
break;
delete []e.znaci;
e.znaci=tmp;
delete[]e.broevi;
e.broevi=b;
++e.n;
}
return in;
}
friend class ComplexNumber;
};
This is only a part of my code.
While compiling I get these two following errors:
error: 'double ComplexNumber::imaginary' is private
error: 'double ComplexNumber::real' is private
On this line:
in>>e.broevi[e.n].real>>e.broevi[e.n].imaginary;
Can you please point out where my mistake is?

Answer 1

Your operator>> is a friend of Equation, so it can access private fields of Equation. But, it is not a member of Equation, and it is not a friend of ComplexNumber, so it can't access private fields of ComplexNumber.
The simplest solution is to add a friend operator>> to ComplexNumber, and then use that in Equation's operator>>:
class ComplexNumber {
double real;
double imaginary;
public:
friend istream& operator >>(istream &in, ComplexNumber &cn) {
in >> cn.real >> cn.imaginary;
return in;
}
};
class Equation {
...
public:
...
friend istream& operator >>(istream &in, Equation &e) {
...
//in >> e.broevi[e.n].real >> e.broevi[e.n].imaginary;
in >> e.broevi[e.n];
...
}
};
However, if that is not allowed for your assignment, then you can instead move your stream logic to a member method of Equation for its operator>> to call, and then that method will have access to the private fields of ComplexNumber:
class ComplexNumber {
double real;
double imaginary;
public:
friend class Equation;
};
class Equation {
...
void read(istream &in) {
// your logic here...
}
public:
...
friend istream& operator >>(istream &in, Equation &e){
e.read(in);
return in;
}
};