Question

How does virtual functions work behind the scenes in Inheritance ?
Does the compiler treat virtual functions specially ?

Answer 1

Yes, virtual methods are treated differently by the compiler and the runtime. The JVM specifically utilizes a virtual method table for virtual method dispatch:

An object’s dispatch table will
contain the addresses of the object’s
dynamically bound methods. Method
calls are performed by fetching the
method’s address from the object’s
dispatch table. The dispatch table is
the same for all objects belonging to
the same class, and is therefore
typically shared between them. Objects
belonging to type-compatible classes
(for example siblings in an
inheritance hierarchy) will have
dispatch tables with the same layout:
the address of a given method will
appear at the same offset for all
type-compatible classes. Thus,
fetching the method’s address from a
given dispatch table offset will get
the method corresponding to the
object’s actual class.