C++ Destructor: cannot access private member declared in class - c++

Question

I am trying to create a simple program in C++ that creates lists of movies using 2 classes: Movie, which contains details of one movie, and Movies, which contains a name and a vector of Movie objects. The whole point is that the user should only interact with the class Movies, therefore I have chosen to make all the members (both data and methods) of the Movie class private.
I keep getting the following error if I let Movie::~Movie() as it is, but if I comment it in both .h and .cpp, it works just fine.
I have explicitly made Movies class a friend of Movie class, so it can access all its members.
error from Visual Studio Community 2019
Movie.h:
#pragma once
#include<iostream>
#include<string>
class Movie
{
friend class Movies;
private:
std::string name;
std::string rating;
int watchedCounter;
int userRating;
std::string userOpinion;
// methods also private because the user should only interact with the Movies class, which is a friend of class Movie
std::string get_name() const;
Movie(std::string nameVal = "Default Name", std::string ratingVal = "Default Rating", int watchedCounterVal = 0, int userRatingVal = 0, std::string userOpinionVal = "");
~Movie();
};
Movie.cpp:
#include "Movie.h"
// Name getter
std::string Movie::get_name() const
{
return this->name;
}
///*
// Destructor
Movie::~Movie()
{
std::cout << "Movie destructor called for: " << this->name << std::endl;
}
//*/
// Constructor
Movie::Movie(std::string nameVal, std::string ratingVal, int watchedCounterVal, int userRatingVal, std::string userOpinionVal) : name{ nameVal }, rating{ ratingVal }, watchedCounter{ watchedCounterVal }, userRating{ userRatingVal }, userOpinion{userOpinionVal}
{
std::cout << "Movie constructor called for: " << name << std::endl;
}
Movies.h:
#pragma once
#include<iostream>
#include<vector>
#include "Movie.h"
class Movies
{
private:
std::string listName;
std::vector<Movie> vectOfMovies;
static int listNumber;
public:
Movies(std::string listNameVal = "Default User's Movie List ");
~Movies();
std::string get_listName() const;
void addMovie(Movie m);
};
Movies.cpp:
#include<string>
#include "Movies.h"
int Movies::listNumber = 0;
// Constructor
Movies::Movies(std::string listNameVal) : listName{listNameVal}
{
++listNumber;
listName += std::to_string(listNumber);
std::cout << "MovieS constructor called for: " << listName << std::endl;
}
// Destructor
Movies::~Movies()
{
std::cout << "MovieS destructor called for: " << listName << std::endl;
}
std::string Movies::get_listName() const
{
return this->listName;
}
//Add movie to list of movies
void Movies::addMovie(Movie m)
{
this->vectOfMovies.push_back(m);
}
And the main .cpp file:
#include <iostream>
// #include "Movie.h"
#include "Movies.h"
int main()
{
Movies moviesObj;
moviesObj.get_listName();
return 0;
}

Answer 1

If the constructor/destructor is declared as private, then the class cannot be instantiated. If the destructor is private, then the object can only be deleted from inside the class as well. Also, it prevents the class from being inherited (or at least, prevent the inherited class from being instantiated/destroyed at all).
The use of having destructor as private:
Any time you want some other class to be responsible for the life cycle of your class' objects, or you have reason to prevent the destruction of an object, you can make the destructor private.
For instance, if you're doing some sort of reference counting thing, you can have the object (or manager that has been "friend"ed) responsible for counting the number of references to itself and delete it when the number hits zero. A private dtor would prevent anybody else from deleting it when there were still references to it.
For another instance, what if you have an object that has a manager (or itself) that may destroy it or may decline to destroy it depending on other conditions in the program, such as a database connection being open or a file being written. You could have a "request_delete" method in the class or the manager that will check that condition and it will either delete or decline, and return a status telling you what it did. That's far more flexible that just calling "delete".
So, I suggest that you could declare ~Movie(); as public. Then, the problem will be solved.