下面程序的运算结果是( )。 #include<iostream> using namespace std; class A public: virtual void fun()=0; ; class B:public A public: void fun() cout<< new file << ; ; class C:public A public: void fun() cout<< open file << ; ; void main() A a, * p; B b;C c; p=&c; p->fun(); p=&b;
A.new file open file
B.new file new file
C.编译出错
D.open file new file