填空题
完成下面程序中的show函数的定义，使其运行结果如下：
In base
In derived
程序清单如下：
#include
using namespace std;
class base
{
pubhc :
virtual void print1
{
cout << "In base" << endl;
}
};
class derived: public base
{
public :
void print2 { cout << "In derived" << endl; }
};
void show(base * pb,void (base:: * pf) 3 )
{
4
}
void main5
{
base b;
derived d ;
show ( &b, base::print);
show ( &d, base::print);
}