Re: Vptr
MC wrote:
I have another naive question. I have been trying to understand the
polymorphysim implementation in C++.
I believe that most of the compilers implement it using vptr and
vtables.
My question is when for every object of a class (which has a virtual
member) if vptr points to the same vtable, why does every object has
a copy of the same vptr?
That's not true, objects of the same class can have different vtables. This
happens if they are not exactly of that class but of a derived class.
If you have a debugger that shows the vtable pointer, you could output the
pointer in the base-class constructor and then again in the derived class
constructor for the same object. You would then see that the same pointer
has different values. This also means the value changes during construction
and destruction.
Uli
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