Doubt about pointers..?

#include %26lt;iostream%26gt;


using namespace std;





class base{





int i;


public:


void set_i(int num){i=num;}


int get_i(){ return i;}





};


class derived:public base{





int j;


public:


virtual void set_j(int num){j=num;}


int get_j(){ return j;}





};








void main(){





base *bp;


derived d;





bp=%26amp;d;





bp-%26gt;set_i(10);


bp-%26gt;set_j(20); // compiler complains





cout%26lt;%26lt;bp-%26gt;get_i();


cout%26lt;%26lt;bp-%26gt;get_j();// compiler complains





}


In the above mentioned C++ program, can someone guide me why compiler complains on those two lines when I have assigned the address of the deriver class object to pointer of base class? Also, what code should I write to access that method of derived class using pointers?





Thanks in advance.


ss

Doubt about pointers..?
well, bp is a base pointer. and class base doesn't have set_j() and get_j(), therefore it complains.





if you call d.set_j() or d.get_j(), then it works. but you always need either an object or a pointer to an object of class 'derived' to call set_j or get_j.
Reply://They way you program, you should tell the compiler explicitly that you want to access a particuler class method, i think you should read about inheritance.





void main(){





base *bp = new derived();





bp-%26gt;set_i(10); // it will only access base class method


((derived*)bp)-%26gt;set_j(20); // it will access derived class mthod


((derived*)bp)-%26gt;set_i(30);// it will access inherited method in derived class





cout%26lt;%26lt;bp-%26gt;get_i();// it will only access base class method


cout%26lt;%26lt;((derived*)bp)-%26gt;get_j();// it will access derived class mthod





}