若有以下程序：
#include〈iostream〉
using namespace std;
class Base
public:
Base ( )
x=0;
int x;
;
class Derived1 : virtual public Base
public:
Derived1()
x=10;
;
class Derived2 : virtual public Base
public:
Derived2()
x=20;
;
class Derived : public Derived1,protected Derived2
;
int main()
Derived obj;
cout〈〈obj.x〈〈end1;
return 0;
该程序运行后的输出结果是〈u〉 【15】 〈/u〉。
