Creating a list pointer that points to other objects

Question

list<Book*> books;
list<Book>::iterator pos, last;

Book Administrator::addBook()
{
    Book *newBook = new Book();
    cout << "Would you like to enter a book?" << endl;
    cin >> userInput;
    cout << endl;

    if (userInput == "yes")
    {

        cout << "What is the title of the book you want to enter?" << endl;
        cin >> title;

        cout << "What is the author of the book you want to enter?" << endl;
        cin >> author;

        cout << "What is the ISBN of the book you want to enter?" << endl;
        cin >> ISBN;

        cout << endl;

        newBook->setTitle(title);
        newBook->setAuthor(author);
        newBook->setISBN(ISBN);
        newBook->setAvailability(true);

        books.push_back(newBook);

    }
    return *newBook;
}

void Administrator::printBookDetails()
{

    books.begin()->setPrevBook(NULL);
    for (pos = books.begin(); pos != books.end(); ++pos)
    {
        cout << pos->getTitle() << "\n"
            << pos->getAuthor() << "\n"
            << pos->getISBN() << "\n"
            << pos->getAvailability() << "\n"
            << "******************************" << endl;

        if (pos != books.begin())
        {
            last->setNextBook(&*pos);
            pos->setPrevBook(&*last);
        }
        last = pos;
    }
    books.back().setNextBook(NULL);

}

Can someone help me finish off this project please, these are my two functions addBook and printbookDetails . These are in my Admin class.

I would like the books i create on the heap to be stored in list< book*> books as i want to reference them in another class.

I've gotten a bit of help on here so far in regards to pointers and i know its something to do with me not linking the pointers to the correct objects.

My printBookDetails is giving me trouble, the first line books.begin()->setPrevBook(NULL); is saying i need a pointer-to-class type but when i put the -> i still have an error.

Book Guest::searchBook(Book* search)
{

    string searchBook;
    cout << "What book would you like to search for?" << endl;
    cin >> searchBook;

    printBookDetails();


}

What id like to do is use the searchBook function above in my Guest class to reference the books in the list at a later time but when i cannot seem to get my pointers right.

Can someone please put me on the right track.

Canyou tell me what books.begin()->setPrevBook(NULL) is for? — RichardPlunkett
– RichardPlunkett, Commented Nov 24, 2013 at 23:32
It looks a little bit like you are trying to connect up all your books into a double-linked list, whose nodes are Book objects. And that you are doing this within the Books held by a std::list<>. Is there some reason you arent just using the std::list, all the other setNextBook/setPrevBook stuff is likely to cause you trouble. As for the line itself, begin() is a like a pointer to an item, just like pos, so see me answer below for fix. — RichardPlunkett
– RichardPlunkett, Commented Nov 24, 2013 at 23:37
Sure, our lecturer wants us to have a link for all books, so when starting the iteration, i link the first element of the list to NULL — user2757842
– user2757842, Commented Nov 24, 2013 at 23:37

RichardPlunkett · Accepted Answer · 2013-11-24 23:23:54Z

2

for (pos = books.begin(); pos != books.end(); ++pos)

Here, pos is an iterator, over your list. Iterators are like pointers to list entries. But each of your list entries is also a pointer to a book, not a book itself. So, you need code like: (*pos)->getTitle() when trying to access member functions for those elements.

answered Nov 24, 2013 at 23:23

RichardPlunkett

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