Question

I’m trying to get my head around why I can’t overwrite a subclass object with another subclass object if they share base class.

Say that Letter is the base class. A and B are subclasses. The following doesn’t seem to work:

Letter* a_p = new A();
Letter* b_p = new B();

delete a_p;
*a_p = *b_p;

My ambition is to change what is located at a certain adress so that all pointers to the adress in question changes what they point to. In the above example, I’d like to somehow change the “content” of a_p to a copy of the “content” of b_p.

Is this possible somehow?

Answer 1

If you are doing a copy of the object and the type of the pointer is the base class, you lose all information about the subclasses.

And since you delete a_p, doing *a_p= is wrong because a_p is pointing to a memory not anymore allocated.

Why not just doing : a_p = b_p; ?