virtual

#include <cstdio>

struct Object
{
    virtual int get_size() = 0;
};

struct Zero : Object
{
    int get_size() {return 0;}
};

struct One : Object
{
    int get_size() {return 1;}
};

struct Two : Object
{
    int get_size() {return 2;}
};

int main()
{
    Object *Mass[3];

    /* Заполним массив */
    Mass[0] = new Zero;
    Mass[1] = new One;
    Mass[2] = new Two;

    for (unsigned int i = 0; i < 3; i++)
        printf("%d\n", Mass[i]->get_size());
}