Access friend class's private member

Question

I'm trying to write a console application like Twitter. User and UserList classes including each other. I'm trying to access to following user's followers. UserList class is used for linked list.

//User.h

#pragma once

#include <iostream>
#include <string>

using namespace std;

class UserList;
class User
{
   friend class UserList;
private:
   string userName;
   string personalComment;
   UserList *followed;
   UserList *following;
   int followedNumber;
   int followingNumber;
   //TWEET
   UserList *blocked;
   User* next;
public:
   User();
   User(string&,string&);
};

//UserList.h
#pragma once

#include <iostream>
#include <string>

using namespace std;


class User;

class UserList{
private:
    User *root;
public:
    UserList();
    ~UserList();
    void addUser(string&,string&);
    bool checkUser(string&);
    User& findUser(string&);
    void printList();
};

Firstly, I wrote a function to find following user.

//userList.cpp
User& UserList::findUser(string& name)
{
   User *temp=root;
   while(temp!=NULL)
   {
       if(!name.compare(temp->userName))
       {
            return temp;
       }
       temp= temp->next;
    }
    temp= temp->next;
    return temp;
}

For example user1 wants to follow user2. I want to check does user1 already follow user2.( checkUser(username) looks for a user in a list and return bool)

//main.cpp in main()
if(users.findUser(user1name).following->checkUser(user2name))
{
            cout<<"Err: The user '"<< user1name << "' has already followed '"<<user2name<<"'!"<<endl;
} 

But there is a "UserList* User::following is private" error and "within this context"

How can I access this user's lists?

Answer 1

In general you should not put logic of your classes in the main. Your issue can be solved for example by adding a method to User that tries to add another user instead of doing this in the main. Something like this:

User::FollowOther(std::string other){
    if(this->following->checkUser(other)) {
        cout<<"Err: The user '"<< userName << "' has already followed '"<<other<<"'!"<<endl;
    }
    /*...*/
} 

The error you got is because User::following is private in User. Private members can only be accessed from within the class. The exception is: You can access private members from within a different class that is declared as friend. But you cannot access private members in the main. Btw, I am not at all a fan of declaring friends, because it breaks encapsulation and makes the relation between classes less obvious, but thats just my personal opinion.