Final answer:
Dynamic cast is used in C++ for runtime type checking within class hierarchies. It is true that it casts a pointer or reference to a related type; specifically, it safely performs downcasting and checks for validity during runtime, returning nullptr or throwing an exception if the cast is not valid.
Step-by-step explanation:
The statement is true. A dynamic cast in C++ is a cast that is used at runtime to safely convert pointers or references of one type to a pointer or reference of another type, within the hierarchy of classes. The dynamic cast is only applicable to pointers or references of classes that are polymorphic, which means the classes have at least one virtual function. It's a type of casting operator used to perform safe down casting and to determine if the conversion is valid during runtime.
For example, if Base is a base class and Derived is a class derived from Base, and given a Base pointer pointing to a Derived object, a dynamic cast can be used to obtain a pointer to the Derived class:
Derived *derivedPtr = dynamic_cast<Derived*>(basePtr);
However, if the cast is not valid because the actual object is not of the target type or a compatible type, the dynamic cast will return nullptr for pointers or throw a bad_cast exception for references.