Zapisanie obiektu do pliku

#ifndef BOOK_H
#define BOOK_H
#include<string>
#include<vector>
#include<iostream>
#include<fstream>

class book
{
public:
std::string Author, Title;
int Year;
book(){}
book(std::string author, std::string title, int year);
friend struct library;
friend std::ostream& operator<<(std::ostream& out, book const& book);
~book(){}
};

struct library
{
public:
friend class book;
std::vector<book> books;
void add_book(const book& value);
};


#endif // BOOK_H 

 #include "book.h"

book::book(std::string author, std::string title, int year)
:Author(author), Title(title), Year(year){}

std::ostream& operator<<(std::ostream& out, book const& book)
{
return out<<book.Author<<book.Title<<book.Year;
}

void library::add_book(const book& value)
{
std::fstream file;
file.open("data.txt", std::ios::app);
books.push_back(value);
file<<value;
file.close();
}

class cObj{
    public:
        cObj(string Data1, string Data2, string Data3);
        string sData1;
        string sData2;
        string sData3;
};
cObj::cObj(string Data1, string Data2, string Data3){
    sData1 = Data1;
    sData2 = Data2;
    sData3 = Data3;
}
 
vector <cObj> vVector;
int main()
{
    vVector.emplace_back("1", "2", "3");
    vVector.emplace_back("4", "5", "6");
    vVector.emplace_back("7", "8", "9");
    vVector.emplace_back("10", "11", "12");
 
    fstream iFile("data.txt", ios::out);
    for(auto &Obj : vVector)
      iFile << Obj.sData1 << " " << Obj.sData2 << " " << Obj.sData3 << "\n";
}