C++ Programming/Programming Languages/C++/Code/Keywords/dynamic cast

The dynamic_cast keyword is used to casts a datum from one pointer or reference of a polymorphic type to another, similar to static_cast but performing a type safety check at runtime to ensure the validity of the cast. Generally for the purpose of casting a pointer or reference up the inheritance chain (inheritance hierarchy) in a safe way, including performing so-called cross casts. Syntax TYPE& dynamic_cast<TYPE&> (object); TYPE* dynamic_cast<TYPE*> (object); The target type must be a pointer or reference type, and the expression must evaluate to a pointer or reference. If you attempt to cast to a pointer type, and that type is not an actual type of the argument object, then the result of the cast will be NULL. If you attempt to cast to a reference type, and that type is not an actual type of the argument object, then the cast will throw a std::bad_cast exception. When it doesn't fail, dynamic cast returns a pointer or reference of the target type to the object to which expression referred. struct A { virtual void f() { } }; struct B : public A { }; struct C { }; void f () { A a; B b; A* ap = &b; B* b1 = dynamic_cast<B*> (&a); // NULL, because 'a' is not a 'B' B* b2 = dynamic_cast<B*> (ap); // 'b' C* c = dynamic_cast<C*> (ap); // NULL. A& ar = dynamic_cast<A&> (*ap); // Ok. B& br = dynamic_cast<B&> (*ap); // Ok. C& cr = dynamic_cast<C&> (*ap); // std::bad_cast } C++ Programming