Question

I have:

class A {...};

class B : public A {...};

class C : public B {...};

Then I’m storing C instance as void*:

C *instance = new C();
void *pC = instance;

Is it ok to make this:

B *pB = reinterpret_cast<B*>(pC);

Or I have to cast to C* only?

PS: I have more classes derived from B in my program and I’m not sure if’s ok to cast like i’m doing (to B*).

Why void*: I’m using void *userdata' field of physical body class in box2d engine. I can’t store my class there in other way

Answer 1

I would suggest casting it back to the original C* then do a dynamic_cast to B* in order to follow the rules of C++ – although you should avoid casting to void* in the first place and instead use a base pointer (A*) instead of void ptr.