Array of objects prints blank string - c++

Question

(The issue has been solved and the solution has been added as comment line to main.cpp)
The problem I'm having is described in the main.cpp file. I already checked another questions about this and none of them really helped.
I'm trying to create a console application with C++ where you can add BOOKS to the LIBRARY. In the library class, there is a displayInfo() function which displays the info of a particular book. It can display integer or double valued informations without having a problem however it is having a trouble when I try to display string typed informations. It just prints blank. Let me give you a little sample of my code.
Here is Book.h
#ifndef BOOK_H
#define BOOK_H
#include <string>
class Book
{
friend class Library;
public:
void setName();
std::string getName();
private:
std::string nameOfBook;
};
#endif
Book.cpp
#include "Book.h"
#include <iostream>
#include <string>
using namespace std;
void Book::setName()
{
string nameOfBook;
cout << "Please enter the name of the book: ";
cin >> nameOfBook;
this->nameOfBook = nameOfBook;
}
string Book::getName()
{
return nameOfBook;
}
Library.h
#ifndef LIBRARY_H
#define LIBRARY_H
#include "Book.h"
#include <array>
class Library
{
private:
std::array <Book , 10> bookArray; // I have to use this
public:
void addBook();
void displayInfo();
};
#endif
Library.cpp
#include "Library.h"
#include "Book.h"
#include <iostream>
#include <string>
#include <array>
using namespace std;
void Library::addBook()
{
bookArray[0].setName();
}
void Library::displayInfo()
{
cout << "The book: " << bookArray[0].getName() << endl;
}
And main.cpp
#include <iostream>
#include "Book.h"
#include "Library.h"
#include <string>
#include <array>
using namespace std;
int main()
{
// The problem is solved
// Create the objects out of the loop
// Library obj1 <---- this solved it
while (true)
{
int number; // Ask user what to do
cout << "Press 1 to add a book\n"
<< "Press 2 to display info\n"
<< "Press 0 to quit\n";
cin >> number;
if (number == 1) // Add a book
{
Library obj1; // <------ THIS IS WRONG
obj1.addBook(); // Consider we named the book as 'Fly'
}
else if (number == 2)
{
Library obj1; // <------ THIS IS WRONG
obj1.displayInfo(); // ******* The output I'm expecting is The Book: Fly
// But instead, it only gives me The Book:
// I have 4 more strings like this in the main project and all of them have the same problem
}
else if (number == 0) // Everything else
{
break;
}
else
{
cout << "Wrong input\n";
continue;
}
}
}
Edit:
I coded this with VS Code and compiled it with MinGW (8.2.0) if it matters.

Answer 1

one problem in your code is that you have many instances of a library class so addBook is landing in one object and displayInfo in a new one (empty one)
you have to:
int main()
{
Library obj1; // declare the lib in scope for all the cases
while (true)
{
int number; // Ask user what to do
cout << "Press 1 to add a book\n"
<< "Press 2 to display info\n"
<< "Press 0 to quit\n";
cin >> number;
if (number == 1) // Add a book
{
obj1.addBook(); // Consider we named the book as 'Fly'
}
else if (number == 2)
{
//Library obj1;
obj1.displayInfo(); // ******* The output I'm expecting is The Book: Fly
// But instead, it only gives me The Book:
// I have 4 more strings like this in the main project and all of them have the same problem
}
else if (number == 0) // Everything else
{
break;
}
else
{
cout << "Wrong input\n";
continue;
}
}
}

Answer 2

u are creating the object again in every iteration of the loop. therefore overwriting the old object that has been given a name.