c++-虚析构函数

虚析构函数

#define _crt_secure_no_warnings
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <fstream>


using namespace std;

class a
{
public:
    a() {
        cout << "a()..." << endl;
        this->p = new char[64];
        memset(this->p, 0, 64);
        strcpy(this->p, "a string..");
    }

    virtual void print()
    {
        cout << "a: " << this->p << endl;
    }

    virtual ~a() {
        cout << "~a()..." << endl;
        if (this->p != null) {
            delete[]this->p;
            this->p = null;
        }
    }
private:
    char *p;
};

class b :public a
{
public:
    b() //此刻会触发a()
    {
        cout << "b()..." << endl;
        this->p = new char[64];
        memset(this->p, 0, 64);
        strcpy(this->p, "b string..");
    }

    virtual void print()
    {
        cout << "b: " << this->p << endl;
    }

    virtual ~b() {
        cout << "~b()..." << endl;
        if (this->p != null) {
            delete[] this->p;
            this->p = null;
        }
    }
private:
    char *p;
};


void func(a *ap)
{
    ap->print();//在此发生多态

}

void deletefunc(a *ap)
{
    delete ap; //此刻ap->~b() //~b() ---> ~a()
}

void test()
{
    //a *ap = new a;
    //func(ap);
    b *bp = new b;
    func(bp);

    deletefunc(bp);
}

int main(void)
{
    test();
    

    b bobj;

    //bobj.~b();
    return 0;
}