C++ unsure how to use one class as a variable in another class

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C++

Hi there!
So, my assignment is to make a book inventory from a file that gets read by the program and put into a linked list. All of the classes, members, constructors and functions seen below are required to be in the program. The only added constructed I add is

Date(unsigned int, unsigned int, unsigned int);

What I have tried:

The error I'm getting just says "warning: unused variable 'published'.

I don't think I'm using

Date *published

correctly in

class Book

. I tried to make a struct in

class Date

out of the variables in there, but that seemed to only make my problems worse.

I would appreciate any nudge in the right direction. Thanks! In the name of saving space, I've left out some stuff that I think is working fine, but I can add back in here if it would be helpful.

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

class Date{
public:
    unsigned int day;
    unsigned int month;
    unsigned int year;
    Date(void);
    Date(unsigned int, unsigned int, unsigned int);
    ~Date(void);
};

Date::Date(void){
    day = 0;
    month = 0;
    year = 0;
}

Date::Date(unsigned int day, unsigned int month, unsigned int year){
    day = day;
    month = month;
    year = year;
}

Date::~Date(void){
}

class Book{
public:
    string title;
    string author;
    Date *published;
    string publisher;
    float price;
    string isbn;
    unsigned int pages;
    unsigned int copies;
    Book(void);
    Book(string, string, Date, string, float, string, unsigned int, unsigned int );
    ~Book(void);
};

Book::Book(void){
    title = "";
    author = "";
    Date *published = NULL;
    publisher = "";
    price = 0;
    isbn = "";
    pages = 0;
    copies = 0;
}

Book::Book( string title, string author, Date published, string publisher,
           float price, string isbn, unsigned int pages, unsigned int copies){
    title = title;
    author = author;
    published = published;
    publisher = publisher;
    price = price;
    isbn = isbn;
    pages = pages;
    copies = copies;
}



void LinkedList::print_list(void){
    Node *temp = head;
    while( temp != NULL ){
        cout << temp->book->title << endl;
        cout << temp->book->author << endl;
        cout << temp->book->published << endl;
        cout << temp->book->publisher << endl;
        cout << temp->book->price << endl;
        cout << temp->book->isbn << endl;
        cout << temp->book->pages << endl;
        cout << temp->book->copies << endl;
        temp = temp->next;
        cout << endl;
    }
}



int main()
{
    LinkedList myList;
    ifstream myfile("booklist.txt");

    string title;
    string author;
    Date published;
    string publisher;
    float price;
    string isbn;
    unsigned int pages;
    unsigned int copies;

    while( myfile ){
        myList.insert_front( new Book(title, author, published, publisher,
                                      price, isbn, pages, copies));

        myfile >> title;
        myfile >> author;
        myfile >> publisher;
        myfile >> price;
        myfile >> isbn;
        myfile >> pages;
        myfile >> copies;
    }

    myList.print_list();

    return 0;
}