I was making my way through the documentation of the c++ language on this website and I was reading about type-casting, they were using the term "valid complete object" quite a bit, but I don't know what it means, so I was hoping you could tell me what exactly counts as a "valid complete object"
Its purpose is to ensure that the result of the type conversion is a valid complete object of the requested class.
In this context, it saying that the result of a dynamic_cast (when used correctly, from a polymorphic base class to one of its derived classes) is guaranteed to be a complete and valid class.
If you misused static_cast, which doesn't make this guarantee, and the base class pointer/reference was referring to a class other than the one you cast the pointer/reference to, then the pointer/reference will end up referring to an object which very probably has the wrong size and layout.
Not sure I've been esp. clear, but that's the gist of it.