I have a function under Base class and at the definition tine of this base class function I need to call another function which is define under the Derived class. how to do this?? My class declaration is below Code: class Base{ public: void showdata(double); }; class Derived : public Base{ public: inline double F(double x) { return exp(-x) + x*x; } Define the function below : Code: void Base::showdata(double a) { std::cout<<"The value of the Function : " << F(a); } and the main function : Code: int main() { //Base obj; Derived obj; obj.F(1.0); return 0; } I'm getting an error : I know this is a correct error but I need to call a derived class function into the base class function.Is it possible any how?? or I have to go different way like template etc So how to solve this problem. With Warm Regards sdmahapatra