填空题
下列程序的输出结果是非曲直{{U}} 【15】 {{/U}}。
#include＜iostream, h＞
class base
{
int x, y;
public:
base(int i, int j){x=i; y=j;}
virtual int add(){return x+ y;}
};
class three: public base
{
int z;
public:
three(int i, int j, int k) :base(i, j){z=k; }
int add() { return (base:: add()+z); }
};
void main()
{
three * q=new three(lO,20,30);
cout＜＜q-＞add()＜＜end1;
}