[C++知识库]【无标题】

#include <stdio.h>

typedef struct {
	int age;
	void (*run)(void); // 假设为虚函数
} Animal;
typedef struct {
	Animal a;
	int b;
	void (*write)(void);
}Person;

void AnimalRun() {
	printf("Animal run\n");
}
void PersonRun() {
	printf("Person run\n");
}
void PersonWrite() {
	printf("Person write\n");
}

Animal ConstructionAnimal(void) {
	Animal a = { 0, AnimalRun };
	printf("Construct Animal\n");
	return a;
}
void DeconstructionAnimal(Animal* animal) {
	printf("Deconstruct Animal\n");
	animal->age = 0;
	animal->run = NULL;
}

Person ConstructionPerson(void) {
	printf("Construct Person\n");
	Animal a = ConstructionAnimal(0);
	Person b = { {0, PersonRun}, 0, PersonWrite }; // 子类继承父类虚函数的重写
	return b;
}
void DeConstructionPerson(Person* person) {
	printf("Deconstruct Person\n");
	DeconstructionAnimal(&person->a);
	person->b = 0;
	person->write = NULL;
}

void test(Animal* p) {
	p->run();
	// c++ 不能通过父类访问子类的未重写的函数(父类访问子类重写的函数就是c++里的动态的多态)
}
int main(void) {
	Animal* p = NULL;
	Animal a = ConstructionAnimal(); // 编译器默认调用构造函数与析构函数
	Person b = ConstructionPerson();
	p = (Animal*)&b;
	test(&a);
	test(&b); // 父类指针调用子类的重写的方法.
	DeconstructionAnimal(&a);
	DeConstructionPerson(&b);
	system("pause");
	return 0;
}