求解释此题~~~~~~~~~

#include <iostream>using namespace std;struct Base{Base():i(1){}int i;};struct Derived:Base{Derived():i(2){}int i;};int main(){Base b[5];Derived d[5];for(int i=0;i<5;i++){b[i] = d[i];cout<<b[i].i<<endl;}cout<<"-----------------------"<<endl;
Base *p = d;for(i=0;i<5;i++)cout<<p[i].i<<endl;return 0;}