虚析构和纯虚析构

#include<iostream>
#include<string>
using namespace std;
class animal {
public:
	//构造函数
	animal()
	{
		cout << "animal的构造函数调用" << endl;
	}
    //纯虚函数
	virtual void speak()
	{
		cout << "动物在说话" << endl;
	}
	//虚析构
	virtual ~animal()
	{
		cout << "animal的析构函数调用" << endl;
	}
};
class cat:public animal {
public:
	//构造函数
	cat(string name) {
		this->name = new string(name); //在堆区创建内存
		cout << "cat的构造函数调用" << endl;
	}
	void speak()
	{
		cout <<*name<< "小猫在说话" << endl;
	}
	//写一个析构函数释放堆区内存
	virtual ~cat() {
		if (name != NULL)
		{
			cout << "cat的析构函数调用" << endl;
			delete name; //释放堆区内存
			name = NULL;
		}
	}
	string* name;
};
void test()
{
	animal* a =new cat("tom");
	a->speak();
	delete a; //如果不在析构函数前加virtual,就只会调用父类析构函数
}
int main()
{
	test();
	system("pause");
	return 0;
}