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