第十一周自选阅读二

阅读代码：

#include <iostream>using namespace std;class A{protected:    int x;public:    A(int x)    {        A::x=x;        cout<<"class A"<<endl;    }};class B{private:    A a1;public:    B(int x):a1(x)    {        cout<<"class B"<<endl;    }};class C:public B{private:    A a2;public:    C(int x):B(x),a2(x)    {        cout<<"class C"<<endl;    }};class D:public C{public:    D(int x):C(x)    {        cout<<"class D"<<endl;    }};int main(){    D dobj(10);    return 0;}

预计运行结果：

class A

class B

class A

class C

class D

实际运行结果：