What does "pb may point to just B" mean exactly?
Why it is not safe to use static_cast?
Help needed.THANKS!!!

// static_cast_Operator.cpp
// compile with: /LD
class B {};

class D : public B {};

void f(B* pb, D* pd) {
D* pd2 = static_cast <D* >(pb); // not safe, pb may
// point to just B

B* pb2 = static_cast <B* >(pd); // safe conversion
}