Using an enum from a class (C++) - c++

Question

I'm reading a book on C++ and was writing out some code to practice using the interface and implementation of a class. I've searched for solutions to my issue for a while to no avail.
I have a class with an enumeration inside of it. While trying to instantiate an object of that class, I am having trouble accessing the enum types outside of the class. I have tried using Book::Horror, Biblo::Horror, Biblo::Book::Horror, Horror, and even things like Biblo::Book::Genre::Horror. Can't seem to get it to let me access the types of the enum for the instantiation of my object in the main.cpp file.
Any help is appreciated! The more complex uses of C++ are still new to me. Here is my source:
book.h
#include <iostream>
#include <string>
using namespace std;
namespace Biblo{
class Book{
public:
enum Genre{
No_Genre, Horror, Comedy, Romance, Mystery
};
// The rest of this header is working fine I think, just this enum
class Invalid{}; // Used for throwing errors
Book(int n_ISBN, int n_copyrightYear, string n_title, string n_author, Genre n_genre);
Book();
// Accessors (non-modifying)
int getISBN() const { return ISBN; }
int getCopyrightYear() const { return copyrightYear; }
string getTitle() const { return title; }
string getAuthor() const { return author; }
string getGenre() const;
// Mutators
void changeAuthor(string newAuthor);
private:
int ISBN;
int copyrightYear;
string title;
string author;
Genre genre;
}; // End Book
// Helper Functions go here
bool operator==(const Book& a, const Book& b);
bool operator!=(const Book& a, const Book& b);
} // End Biblo
and main.cpp
#include <iostream>
#include "book.h"
using namespace std;
int main()
{
Biblo::Book book(100, 2012, "The Walrus", "The Eggman", Book::Horror); // THIS LINE GIVES ERROR
cout << "ISBN: " << book.getISBN() << endl;
cout << "Copyright: " << book.getCopyrightYear() << endl;
cout << "Title: " << book.getTitle() << endl;
cout << "Author: " << book.getAuthor() << endl;
cout << "Genre: " << book.getGenre() << endl;
return 0;
}
Edit: here is the book.cpp file
#include <iostream>
#include "book.h"
#include <string>
namespace Biblo{
Book::Book(int n_ISBN, int n_copyrightYear, string n_title, string n_author, Genre n_genre)
:ISBN(n_ISBN), copyrightYear(n_copyrightYear), title(n_title), author(n_author), genre(n_genre)
{
// constructor
}
Book::Book()
:ISBN(0), copyrightYear(0), title(""), author(""), genre(Genre::No_Genre)
{
// Default constructor
}
// Accessors
string Book::getGenre() const
{
if (Book.genre == Genre::No_Genre)
return "No Genre!";
if (Book.genre == Genre::Horror)
return "Horror";
if (Book.genre == Genre::Comedy)
return "Comedy";
if (Book.genre == Genre::Romance)
return "Romance";
if (Book.genre == Genre::Mystery)
return "Mystery";
}
// Mutators
void Book::changeAuthor(string newAuthor)
{
author = newAuthor;
}
// Helper Functions
bool operator==(const Book& a, const Book& b)
{
if (a.getISBN() != b.getISBN())
return false;
if (a.getCopyrightYear() != b.getCopyrightYear())
return false;
if (a.getTitle() != b.getTitle())
return false;
if (a.getAuthor() != b.getAuthor())
return false;
if (a.getGenre() != b.getGenre())
return false;
return true;
}
bool operator!=(const Book& a, const Book& b)
{
return !(a==b);
}
} // End Biblo

Answer 1

It seems you tried everything but the thing you needed! The enum is nested inside the Book class which is within the Biblo namespace. The code you are looking for is:
int main()
{
Biblo::Book book(100, 2012, "The Walrus", "The Eggman", Biblo::Book::Horror);
return 0;
}

Answer 2

You need to include the enum class. eg.:
Biblio::Book::Genre::Horror

Answer 3

Bunch of things that are going wrong really.
As others mentioned your enum is stashed one level deeper than you think it is, and your complaint about fixing it then producing an undefined reference is probably because at that point you bump into the fact there's nothing much initialized, and if you got past that you are returning items somewhat poorly when it comes to the enumerator.
If you use the right name space, quickly put in an actual implementation for the constructor, and get the most immediate return for your enum (an int might work) it should work, and probably look like this:
#include <iostream>
#include <string>
using namespace std;
namespace Biblo{
class Book{
public:
enum Genre{
No_Genre, Horror, Comedy, Romance, Mystery
};
// The rest of this header is working fine I think, just this enum
class Invalid{}; // Used for throwing errors
Book(int n_ISBN, int n_copyrightYear, string n_title, string n_author, Genre n_genre);
Book();
// Accessors (non-modifying)
int getISBN() const { return ISBN; }
int getCopyrightYear() const { return copyrightYear; }
string getTitle() const { return title; }
string getAuthor() const { return author; }
int getGenre() const { return genre; }
// Mutators
void changeAuthor(string newAuthor);
private:
int ISBN;
int copyrightYear;
string title;
string author;
Genre genre;
}; // End Book
Book::Book(int n_ISBN, int n_copyrightYear, string n_title, string n_author, Genre n_genre){
ISBN = n_ISBN; copyrightYear = n_copyrightYear; title = n_title; author = n_author;
};
}
using namespace std;
int main()
{
Biblo::Book book(100, 2012, "The Walrus", "The Eggman", Biblo::Book::Horror); // THIS LINE GIVES ERROR
cout << "ISBN: " << book.getISBN() << endl;
cout << "Copyright: " << book.getCopyrightYear() << endl;
cout << "Title: " << book.getTitle() << endl;
cout << "Author: " << book.getAuthor() << endl;
cout << "Genre: " << book.getGenre() << endl;
return 0;
}
Are you sue the book you're following isn't discussing details such as initializer lists or something else for constructors concurrent to, or previous to, the subjects you're looking at?
The code looked somewhat incomplete.
Edited in line here on SO, so bear with the poor formatting and the merged h/cpp look :)