What is the data type of vptr?

Question

Any class having a virtual function would get an extra hidden pointer which would point to the most derived class.

What is the type of this vptr?

Answer 1

It has no type. It's an implementation detail unspecified by the standard; it is not part of the language.

Note that C++ doesn't say that there has to be a virtual table or a virtual "pointer" at all (though this is the most common implementation of RTTI in C++ toolchains).

Also, your analysis is wrong. In, say, GCC, usually each object gets a vptr that points to the relevant virtual table for that object's type: object has pointer, type has table.

Answer 2

The standard does not guarantee the presence of the virtual table pointer, even though most implementations use it.

As a result, it has no type. It is simply an array of pointers.