In C++, polymorphism requires :

Answer: Runtime polymorphism in C++ requires three things:

• An inheritance relationship: a base class and at least one derived class.

• Virtual functions: the base-class function must be declared virtual so calls can be dynamically dispatched to the derived override at runtime.

• Pointer or reference to base: you must call through a base-class pointer or reference (pointers are acceptable) to avoid slicing and to enable virtual dispatch.

Example: Define a base class with a virtual function, derive a class that overrides it, then call the function through a base-class pointer or reference to invoke the derived implementation at runtime.

Note: This describes runtime (dynamic) polymorphism. Compile-time polymorphism (function overloading or templates) is a different mechanism and does not require virtual functions or base-class pointers/references.