阅读程序1

#include <iostream>using namespace std;class A{    int a;public:    A():a(5){}    virtual void print()const {cout<<a;}};class B:public A{    char b;public:    B(){b='E';}    void print()const {cout<<b;}};void show (A &x){x.print();}int main(){    A d1,*p;    B d2;    p=&d2;    d1.print();    d2.print();    p->print();    show(d1);    show(d2);    return 0;}