Question

Is this the right way to return an object from a function?

Car getCar(string model, int year) {
   Car c(model, year);
   return c;
}

void displayCar(Car &car) {
   cout << car.getModel() << ", " << car.getYear() << endl;
}

displayCar(getCar("Honda", 1999));

I’m getting an error, “taking address of temporary”. Should I use this way:

Car &getCar(string model, int year) {
   Car c(model, year);
   return c;
}

Answer 1

getCar returns a Car by value, which is correct.

You cannot pass that return value, which is a temporary object, into displayCar, because displayCar takes a Car&. You cannot bind a temporary to a non-const reference. You should change displayCar to take a const reference:

void displayCar(const Car& car) { }

Or, you can store the temporary in a local variable:

Car c = getCar("Honda", 1999);
displayCar(c);

But, it’s better to have displayCar take a const reference since it doesn’t modify the object.

Do not return a reference to the local Car variable.