How to use class object as private member in another class?

[akebono]

hi, could someone explain how to implement constructors, copy constructors, and overloaded assignment operators for a class that has another class object as a private member?

for example, in my Vehicle class, one of the private members is Person owner, and Person is a different class..

for the default constructor, i don't need to do anything with the owner right?
for non-default constructors, would i do something like:
owner = Person(name);

for copy constructors, i am not sure. is it like:
owner = theObject.owner;
and same problem for overloaded assignment operators, i am not sure what to do with the "owner" member..

[gcampton]

have a read through http://cplusplus.com/doc/tutorial/ on the various topics you just mentioned (it's a very short concise tutorial), and have a go at writing up some code then posting here with specific questions and some code samples in [c ode] ..blocks.. [/c ode] because as it is, I'm unsure whether you constructor actually passes name in arguments, or whether you are just trying to figure out how to initialize it... or what...

[akebono]

for example, if i have:

class Car{
      public:
                Car(const Car& object);
                Car& operator=(const Car& rightSide);
      private:
                 string manufacturer
                 Person owner;
};

and

class Person{
      public:  
                //code here
      private:
                string name;
};

I don't know how to put the implementation of the copy constructors and overloaded assignment operators for the Car class.. because there is a Person owner private variable, I don't know what to do with this for copy constructor and overloaded assignment operator in Car class.. I need help fast please

[firedraco]

You would just create assignment/copy stuff for Person, then just call them in Car's copy/assignment functions.

[akebono]

oh, so it's exactly like inheritance then?
so would i do

Car::Car(const Car& object) : Person(object),
{   }

and

Car::Car& operator=(const Car& rightSide)
{
      Person::operator=(rightSide);
}

[Zhuge]

That looks fine, except the second part you would probably want owner. instead of Person::

[akebono]

why would i put owner.? wouldn't Person work if it only has one private variable "name"?

[akebono]

umm..i got a lot of errors and changed it to this and it compiled.. is this correct?

Car::Car(const Car& object) : owner(object.owner),
{   }

Car::Car& operator=(const Car& rightSide)
{
      owner.operator=(rightSide.owner);
}

[Zhuge]

The reason Person:: doesn't work is because that's trying to call a static function of the Person class, rather than call the assignment on the instance of Person in the Car (called owner).

Also, I didn't notice before, but it looks like your Person constructor takes a string for the name as a parameter, so you don't want to be passing object.owner; instead you want to pass a name string.

[jsmith]

owner = rightSide.owner;

is preferred to

owner.operator=( rightSide.owner );

although for classes that have "normal" (member-wise) copy semantics, such as this one, you don't even need
to write an assignment operator or a copy constructor... the default member-wise versions provided by the
compiler will suffice.

[Abramus]

Maybe my question is a little off topic, but why the Car class contains a Person object? Shouldn't it reference a Person object instead?

If it's just a poorly chosen example then feel free to ignore me:)