C++ static_cast runtime overhead

Question

See the code below.

a) Does, in this case (simple inheritance, no virtual members), the static cast in B::df() have any overhead (whatsoever)? I found some conflicti

Answer 1

static_cast<T>(e) is equivalent to creating an invented temporary variable v in the following way:

T v(e); //where T is an arbitrary type  and e is an arbitrary expression.

The runtime cost of a static_cast is exactly the cost of the above statement