Lets say we have a class hierarchy. At the bottom we have Base and at the top Derived. How to determine object class even if it is converted to base class pointer.
Base* b = new Derived():
typeid(b).name(); // i want this to tell me that this is actually derived not base object
is there any way other than manual implementation of string field or such and virtual get function?
PS: I talking about compiler-independent solution
make sure the base class has at least one virtual method, include <typeinfo>
and use your current code just with an additional dereferencing, typeid(*b).name()
.
typeid
call is the one place in C++ where you can dereference a nullpointer with well-defined behavior, which implies that it can throw an exception:
C++11 §5.2.8/2:
“If the glvalue expression is obtained by applying the unary*
operator to a pointer and the pointer is a null pointer value (4.10), thetypeid
expression throws thestd::bad_typeid
exception (18.7.3).”