Virtual functions helps to override methods from base class.
If the
Base class and the
Child class both defines the function
method() then the pointer reference of
Base class pointing to the object of
Child class when used to call function
method(); it will call the
Base class function
method()
i.e;
Base * base = new Child();
base->method(); // this will call the Base class method() ; unless untill you declare method() as virtual in base class.
Internal Working :
If compiler finds any virtual function it creates a static array for each class called VTable or Virtual Table. Elements of this VTable are the function pointer to each member function.Since Vtable is a static array it means its object independent.
During object creation compiler creates a secrete data member for the base class. This data memeber is called Virtual Pointer. This Virtual Pointer is inherited by the child class. Respective class instances's virtual pointer points to respective class's VTable. Hence provisioning for overriding.
Virtual Functions can't be static as static functions are tied to a class and not to instance of a class.
