阅读项目，写出执行结果4

#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：

过程分析：

base 是一个虚基类，只有最远派生类的构造函数才会调用虚基类的构造函数，该派生类的其他基类对虚基类的构造函数的调用都会忽略，所以初始化只进行一次

按照继承顺序 对derived1 derived2进行初始化

对myderived中的base型的数据进行初始化

最后执行构造函数中的输出语句