Help with Vector Objects

[xulander]

Hello!

So I am working on creating vector objects, and I am getting an error when trying to run:
In function 'void populateVectors(std::vector<Library, std::allocator<Library> >&, std::vector<Members, std::allocator<Members> >&)':
assign6.cpp:82: error: 'getBook' was not declared in this scope

Ive attached the codes that pertain to this.

class Library
{
	private:
		string book, author, ISBN;
		float price;
		bool available;
		int memberNum;
	public:
		void getBook (ifstream);
		void getAuthor(ifstream);
		void getISBN (ifstream);
		void getPrice (ifstream);
		void getAvailable (ifstream);
		void getNum (ifstream);
		string showBook () const;
};

void Library::getBook (ifstream fin)
{
	fin >> book;
}

string Library::showBook () const
{
	return book;
}

Ignore the vector for members, its another class im using that I havent coded for yet.

void populateVectors(vector<Library>&, vector <Members>&);

int main()
{

	vector<Library> library;
	vector<Members> members;
	populateVectors(library, members);
	return 0;

And the function that calls this is

void populateVectors(vector<Library> &library, vector <Members> &members)
{
	ifstream fin;
	string filename;
	cout << "\n\n. Hello. Please enter the filename (with .txt extension) for the library: ";
	getline(cin, filename);
	fin.open(filename.c_str());
	while(fin.fail())
	{
		cout << "\nBad Filename. Please Re-Enter Filename: ";
		getline(cin, filename);
		fin.open(filename.c_str());
	}
	
	library.push_back(getBook(fin));
	cout << "\nBook name is " << library[0].showBook() << endl;

	fin.close();
}

Am I using pushback correctly with vector objects? I have no idea why it isnt recognizing getBook as a member of the class Library. I have tried searching around the forums for similar problems, but have no encountered any. Thank you!

[xulander]

I've also tried changing the code to

library.push_back(library.getBook(fin));

but it hasn't worked either :\

Also, ideally, I would like to be able to populate the whole class on the same vector. Then push back to a new object, and populate the whole thing before pushing back again. How would I approach that? Would I keep using push_back?

From what im imagining, if i created another constructor(function in object?)

void Library::getAuthor (ifstream fin)
{
	fin >> author;
}

but wrote it as this in the populateVectors function:

library.push_back(getBook(fin)); //after this line in the function
library.push_back(getAuthor(fin)); 

would that just set author in the new vector[1] ?

To clarify, would it be allocated like this:
library[0].showBook()
library[1].showAuthor()
??

Because I am trying to make it so it is like this:
library[0].showBook()
library[0].showAuthor()

Sorry if its hard to understand what Im trying to say. I basically just want to have the 1st object filled fully instead of just filling 1 member of an object, and then pushing to another one.

[Stewbond]

I think what you want is to replace line 15:
library.push_back(getBook(fin));

with:

Library newBook;
newBook.getBook(fin);
library.push_back(newBook);

[xulander]

Thanks, but now I just got a load of errors. Should I copy and paste it all here?

[Stewbond]

A second option is to change:

class Library 
{
    void getBook(ifstream);
    //...
};
void Library::getBook (ifstream fin)
{
	fin >> book;
}

to

class Library 
{
    friend Library getBook(ifstream);
    //...
};
Library getBook (ifstream fin)
{
	Library newLibrary;
	fin >> newLibrary.book;
	return newLibrary;
}

That being said, I think there's a general problem with your design.

To add a book, we have to create another library. Try using 2 classes, "library" and "book". The library class will have options to add books and will store the books in a vector.. The book will have options to add titles, and will store the info about each book. That will make things more intuitive for you. A vector of books makes more sense than a vector of libraries.

[xulander]

What function does the keyword friend play?

[xulander]

And if I just use library to store the books, would it be better if i just used library a s a struct?

EDIT: nvm about the above statement. Would Books be a vector then? I feel like we can just constantly replace books with the next books being read by the file, after storing it into library