Program to display input value using virtual function with class in C++

//program to print out input value using virtual function with class #include<iostream.h> #include<conio.h> class Base { public: int a; virtual void display()                                 { } }; class Derived:public Base { public: virtual void display() { cout<<"Enter a Value of a:"; cin>>a; cout<<"Value of a is :"<<a; } }; int main() { Base *pt; Derived b1; pt=&b1; (*pt).display();//pt->display(); getch(); }