//xujic.cpp
#include <iostream>
#include <string>
using namespace std;
class Animal
{
public:
void breath()
{cout<<"动物要呼吸"<<endl;}
Animal(){cout<<"Animal 构造函数"<<endl;}
};
class Bird:virtual public Animal
{
public: Bird(){cout<<"Bird 构造函数"<<endl;}
};
class Fish:virtual public Animal
{
public: Fish(){cout<<"Fish 构造函数"<<endl;}
};
class FB:public Bird,public Fish
{
public:FB(){cout<<"FB 构造函数"<<endl;}
};
void main()
{
FB f;
}
如果是Bird,Fish 都是虚继承之Animal,
那么 定义FB对象f时,仅仅是调用了一次Animal的构造函数
也就是在调用Bird和Fish的构造函数时,不会再调用Animal的构造函数了,因为它们是virtual继承.
对比试试:
把 Bird的 Virtual 取消:
//xujic.cpp
#include <iostream>
#include <string>
using namespace std;
class Animal
{
public:
void breath()
{cout<<"动物要呼吸"<<endl;}
Animal(){cout<<"Animal 构造函数"<<endl;}
};
class Bird:public Animal
{
public: Bird(){cout<<"Bird 构造函数"<<endl;}
};
class Fish:virtual public Animal
{
public: Fish(){cout<<"Fish 构造函数"<<endl;}
};
class FB:public Bird,public Fish
{
public:FB(){cout<<"FB 构造函数"<<endl;}
};
void main()
{
FB f;
}
Animal 的构造函数则调用了2次: