How exactly serialization works in C++? - c++

Question

Here are my code files:
main.cpp
#include <iostream>
#include <fstream>
#include "Car.h"
#include "Engine.h"
using namespace std;
int main() {
Car* car = new Car(1984);
/* do something here */
delete car;
return 0;
}
Car.h
#ifndef CAR_H
#define CAR_H
#include <iostream>
using namespace std;
#include "Engine.h"
class Car {
public:
Car(int);
virtual ~Car();
void serialize(ostream& s) {
engine.serialize(s);
s << ' ' << yearModel;
}
void unserialize(istream& s) {
engine.unserialize(s);
s >> yearModel;
}
private:
Engine engine;
int yearModel;
};
#endif /* CAR_H */
Car.cpp
#include "Car.h"
Car::Car(int year) {
yearModel = year;
}
Car::~Car() {
}
Engine.h
#ifndef ENGINE_H
#define ENGINE_H
#include <iostream>
using namespace std;
class Engine {
public:
Engine();
virtual ~Engine();
void serialize(ostream& s) {
s << ' ' << engineType;
}
void unserialize(istream& s) {
s >> engineType;
}
private:
int engineType;
};
#endif /* ENGINE_H */
Engine.cpp
#include "Engine.h"
Engine::Engine() {
engineType = 1;
}
Engine::~Engine() {
}
What I want to do in the main.cpp is to save the created Car object to file.txt and later read it from there. How does that exactly work? For example: how do I call the serialization function in Car class?
I'm sorry if I sound like a noob, but this whole serialization thing is pretty new to me.
Edit: Code compiles now when I added 'void' in front of all serialize- and unserialize-functions.

Answer 1

This has nothing to do with serialization: a function needs a return type, even if it is void. So this is wrong:
serialize(ostream& s) // look, no return type.
You probably need to either return void,
void serialize(ostream& s) { /* code as before */ }
or return the stream by reference to allow for chaining:
ostream& serialize(ostream& s) {
return s << ' ' << engineType;
}