填空题
有如下程序：
#include ＜iostream＞
using namespace std;
class ONE
public:
virtual void f() cout＜＜"1";
;
class TWO:public ONE
public:
TWO() cout＜＜"2";
;
class THREE:public TWO
public:
virtual void f() TWO::f(); cout＜＜"3";
;
int main()
ONE aa, *p;
TWO bb;
THREE cc;
p=&cc;
p-＞f();
return 0;
执行上面程序的输出是______。
【参考答案】
2213