Should I use pointers to OOP objects or should a create default constructors? [closed]

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I'm really confused about c++ objects. If an object has to be initialized with parameters (which most objects do), should I create a constructor with parameters and thus always create pointers to my objects when storing them, or should I have an empty constructor with an Init() method which takes the parameters necessary to initialize my objects so that I can have non-pointer fields for my objects?

EDIT: I mean this:

//A.h
class A
{
    public:
        A(int x);
}
//B.h
class B
{
    private:
        A myobject;
}

Will throw IntelliSense: no default constructor exists for class "A"

So I can do this:

//B.h
class B
{
 private:
  A* myobject;
}

OR

//A.h

class A
{
 public:
  A(void);
  void Init(int x);
}

which of those is the right thing to do?

Answer 1

The initializer list feature exists precisely so that you can pass arguments to the constructors of members.

class B {
  A a;
public:
  B();
};

B::B() : a(99) {}

Answer 2

class A
{
public:
    A(int x) {}
};

class B
{
public:
    B(int x, double y) : a(x) {}
private:
    A a;
};

int main()
{
    B b(23, 78.6);
}

You can use an initialiser list to do this. See http://en.cppreference.com/w/cpp/language/initializer_list

Answer 3

You can call the constructor from your B-class, but you have to supply a value to A's constructor.

An example could be this:

class A{
public:
    A( int x ){};
};

class B{
public:
    B( void ) : _my(0){};
private:
    A _my;
};

Alternatively, you could pass a value from B on to A, by e.g.

class A{
public:
    A( int x ){};
};

class B{
public:
    B( int x_b ) : _my(x_b){};
private:
    A _my;
};

I don't know if this exactly solves your problem, but it will make your class a private class of B, without the need of creating pointers and the whole new/delete part that comes with it.

Cheers

Answer 4

Either of the two options you suggested is fine. Which one you should choose will depend on your use-case. Generally I'd prefer the first option while ensuring that you delete A in B's destructor. You should only use an init() method if you ensure that A will correctly report an error if it is used without being initialized.