Why is dynamic casting bad?

dynamic_cast is “bad design” for the simple reason that it violates this purpose, since you need your object to be of some derived type, so it doesn’t suffice to know the base type of it. That being said it still has its use (especially as the world isn’t as simple as Java likes it to be).

Is dynamic cast Safe?

A It will be a safe dynamic cast as long as the argument to dynamic_cast is a valid pointer (including NULL). If you pass a dangling pointer or a value that is garbage, then the call to dynamic_cast is not guaranteed to be safe.

What is the use of dynamic cast operator in C++?

The dynamic_cast operator ensures that if you convert a pointer to class A to a pointer to class B , the object of type A pointed to by the former belongs to an object of type B or a class derived from B as a base class subobject.

What happens if dynamic cast fails?

If a dynamic_cast fails, the result of the conversion will be a null pointer. Because we haven’t checked for a null pointer result, we access d->getName(), which will try to dereference a null pointer, leading to undefined behavior (probably a crash).

Why do we need RTTI in C++?

Run-time type information (RTTI) is a mechanism that allows the type of an object to be determined during program execution. RTTI was added to the C++ language because many vendors of class libraries were implementing this functionality themselves. This caused incompatibilities between libraries.

What is the difference between static and dynamic cast C++?

static_cast − This is used for the normal/ordinary type conversion. This is also the cast responsible for implicit type coersion and can also be called explicitly. You should use it in cases like converting float to int, char to int, etc. dynamic_cast −This cast is used for handling polymorphism.

Why do we need dynamic casting?

In C++, dynamic casting is mainly used for safe downcasting at run time. To work on dynamic_cast there must be one virtual function in the base class. A dynamic_cast works only polymorphic base class because it uses this information to decide safe downcasting.

Does dynamic cast throw?

dynamic_cast will never throw a structured exception ( std::bad_cast , for instance) when used with pointers, but it will probably throw an unstructured exception that you cannot catch when passed an invalid pointer.

When should I use dynamic pointer cast?

dynamic_cast is exclusively used for handling polymorphism. You can cast a pointer or reference to any polymorphic type to any other class type (a polymorphic type has at least one virtual function, declared or inherited).

Why do we need dynamic cast?

In C++, dynamic casting is, primarily, used to safely downcast; i.e., cast a base class pointer (or reference) to a derived class pointer (or reference). It can also be used for upcasting; i.e., casting a derived class pointer (or reference) to a base class pointer (or reference).

What does dynamic cast of a reference return if it fails?

If the cast is successful, dynamic_cast returns a value of type new-type. If the cast fails and new-type is a pointer type, it returns a null pointer of that type. If the cast fails and new-type is a reference type, it throws an exception that matches a handler of type std::bad_cast.