【设计模式】描述先有鸡还是先有蛋

#include <iostream>
using namespace std;

enum TYPE{
HEN, EGG
};

class Egg;

class Hen
{
public:
enum TYPE type;
int wings;
Egg* egg;
Hen(){
type = HEN;
wings = 2;
}
};

class Egg : public Hen
{
public:
enum TYPE type;
int shell;
Egg(){
type = EGG;
shell = 1;
}
};

int main()
{
Hen hen = Hen();
hen.egg = &Egg();
printf("Type of Hen:%d Type of Egg:%d\n", hen.type, hen.egg->type);
printf("Wings of Hen:%d Wings of Egg:%d Shell of Egg:%d", hen.wings, hen.egg->wings, hen.egg->shell);
system("Pause");
}