有以下程序#include ＜iostream＞using namespace std;class Base{ int a;public: Base(int x) { a=x; } void show() { cout＜＜a; }class Derived: public Base{ int b;public: Defived(int i):Base(i+ 1 ),b(i) {} void show() { cout＜＜b; }};int main(){ Base b(5),*pb; Derived d(1); pb=&d; pb-＞show(); return 0;}运行后的打印结果是 【13】 。