C++——虚析构

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;


//虚析构函数
class A
{
public:
    A()
    {
        p = new char[20];
        strcpy(p, "obja");
        printf("A()\n");
    }
     virtual ~A()
    {
        delete [] p;
        printf("~A()\n");
    }
protected:
private:
    char *p;
};

class B : public A
{
public:
    B()
    {
        p = new char[20];
        strcpy(p, "objb");
        printf("B()\n");
    }
      ~B()
    {
        delete [] p;
        printf("~B()\n");
    }
protected:
private:
    char *p;
};


class C : public B
{
public:
    C()
    {
        p = new char[20];
        strcpy(p, "objc");
        printf("C()\n");
    }
    ~C()
    {
        delete [] p;
        printf("~C()\n");
    }
protected:
private:
    char *p;
};




void howtodelete(A *base)
{
    delete base;  //这句话不会表现成多态 这种属性
}

void main()
{
    C *myC = new C; //new delete匹配
    //
    delete myC; //直接通过子类对象释放资源 不需要写virtual （即不使用虚析构）

    //howtodelete(myC); //使用父类对象释放资源，使用虚析构
    
    cout<<"hello..."<<endl;
    system("pause");
    return ;
}