第十二周课后实践：阅读程序

（1）

代码：

#include <iostream>using namespace std;class A{public:    A()    {        a=0;    }    A (int i)    {        a=i;    }    void print()    {        cout<<a<<"  ";    }private:    int a;};class B: public A{public:    B()    {        b=0;    }    B(int i, int j, int k): A(i),aa(j)    {        b=k;    }    //思考：这3处出现的print，有何区别    void print()      //(1)    {        A::print();   //(2)        aa.print();   //(3)        cout<<b<<endl;    }private:    int b;    A aa;};int main(){    B test[2];    test[0]=B(1,4,7);    test[1]=B(2,5,8);    for(int i=0; i<2; i++)        test[i].print();    return 0;}

运行结果：

（2）

代码：

#include <iostream>using namespace std;class A{public:    A(char *s)    {        cout<<s<<endl;    }};class B:public A{public:    B(char *s1, char *s2):A(s1)    {        cout<<s2<<endl;    }};class C:public A{public:    C(char *s1,char *s2):A(s1)    {        cout<<s2<<endl;    }};class D:public B, C{public:    D(char *s1,char *s2,char *s3,char *s4):B(s1,s2),C(s3,s4)    {        cout<<s4<<endl;    }};int main(){    D d("class A","class B","class C","class D");    return 0;}

运行结果：

（3）

代码：

#include <iostream>using namespace std;class Base{public:    Base(char i) { cout<<"Base constructor. --"<<i<<endl; }};class Derived1:virtual public Base{public:    Derived1(char i,char j):Base(i)    {        cout<<"Derived1 constructor. --"<<j<<endl;    }};class Derived2:virtual public Base{public:    Derived2(char i,char j):Base(i)    {        cout<<"Derived2 constructor. --"<<j<<endl;    }};class MyDerived:public Derived1,public Derived2{public:    MyDerived(char i,char j,char k,char l,char m,char n,char x): Derived2(i,j), Derived1(k,l), Base(m), d(n)    {        cout<<"MyDerived constructor. --"<<x<<endl;    }private:    Base d;};int main(){    MyDerived obj('A','B','C','D','E','F','G');    return 0;}

运行结果：

（4）

代码：

#include<iostream>using namespace std;class A{public:   int n;};class B:public A {};   // class B:virtual public A{};class C:public A {};   // class C:virtual public A{};class D:public B,public C{public:    int getn() {return B::n;}};int main(){   D d;   d.B::n=10;   d.C::n=20;   cout<<d.getn()<<endl;   return 0;}

运行结果：