子类重写父类的虚函数后需要调用父类的虚函数

#include<iostream>
#include<vector>
using namespace std;
class BASE
{
public:
virtual void add(){cout<<"BASE";};
};
class A:public BASE
{
public:
virtual void add(){cout<<"A";};
};
class B:public BASE
{
public:
virtual void add(){cout<<"B";};
};
class D:public A,B
{
#define SWITCH(X)\
{\
switch(this->d)		\
{\
case 0:				\
A::X;	\
break;\
case 1:				\
B::X;	\
break;\
default:			\
this->X;	\
}\
}\
;
public:
D(){this->d=5;};
virtual void add(){cout<<"D";};
void print(){SWITCH(add())};
private:
int d;
};

int main()
{
D d;
d.print();
system("pause");
return 0;
}