pointer vs non-pointer members of a class

My questions is, suppose we have two classes A and B. I want to have an object of B in class A.

Should I use,

class A
{
public:
    A();
    ~A();
    B* b;
};

or

class A
{
public:
    A();
    ~A();
    B b;
};

As far as I know, in the first scenario, I can initialize the object *b using new operator and for the second scenario, I can initialize b using an initialization list if I don't want to use the default constructor of class B. Which is more convenient to use?

It depends.

Even if you use the pointer, you can initialize the member in the initialization list, but that's not your biggest concern.

There are advantages and disadvantages to both:

Using a pointer:

Pros:

• the class will be smaller in memory

• you only need a forward declaration to the other class - no need to include the other header in your header

• can use derived objects from B as members

Cons:

• memory management - this is a pretty big one. Do you want the memory to be managed by the class (override destructor, assignment operator and copy constructor)?

Using an object:

Pros:

• no need to worry about memory management

Cons:

• can only use objects of the base class. What if you want to derive from B?

• more memory for each instance

• constructor of B will be called on construction of A

• you need the full definition of B inside the header

I'll edit my answer if I think of more.