有以下程序： #include ＜iostream＞ using namespace std; class Base { public: Base(){} virtual void f1() { cout＜＜"f1 of base"＜＜end1; } ～Base(){} }; class Derive: public Base { public: void fl(int x) { cout＜＜"f1 of derive"＜＜end1; } }; int main ( ) { Base *p; Derive obj1; p=&obj 1; p-＞f1 ( ); return 0; }