opposite operation to dynamic_cast

Question

I have a base class and derivative class, e.g :

class Base {
 public:
  Base();
  virtual doSomthing();
};

class Derivative : class Base {
 public:
  Derivative();
  virtual doSomthing();
};

I know that if I want to change at runtime from the father to son I will do

Derivative& newDer = dynamic_cast<Derivative&>(baseInstance)

my question is how I can do the opposite operation - change from son to the father?

Answer 1

There's no specific cast operation needed. Any Derivative& automatically can be passed for a Base& if they are really have that relation like in

class Derivative : public Base {
                // ^^^^^^
 public:
  Derivative();
  virtual doSomthing();
};

Supposed you tried to do that from a global public scope.

---

my question is how I can do the opposite operation - change from son to the father?

The inheritance relation needs to be accessible in the scope used though. Your example has private inheritance, and it won't work at the public scope.

As mentioned by @StoryTeller and @Peter it will work at the Derivative inner class scope with any class member function or friended function/class.