#include <iostream>
using namespace std;

class CBase
{
public:
    CBase()
    {
        cout<<"I in Base constructor"<<endl;
    }
    virtual ~CBase()
    {
        cout<<"I in Base deconstructor"<<endl;
    }
};

class CDerived : public CBase
{
public:
    CDerived()
    {
        cout<<"I in CDerived constructor"<<endl;
    }
    virtual ~CDerived()
    {
        cout<<"I in CDerived deconstructor"<<endl;
    }
};


int main()
{

    CBase *pBase = new CDerived();
    delete pBase;

    return 0;
}

输出结果

I in Base constructor
I in CDerived constructor
I in CDerived deconstructor
I in Base deconstructor

      以前一直觉得virtual的指定是可有可无的，现在才知道，如果不制定virutal，那么I in CDerived deconstructor就不会调用。这个与construtor完全不一样，事实上也正是这样把他/它忽略了。

      接着就要想想如何实现的呢？

先来看看构造函数
004012CF   .  894D F0       mov     [ebp-10], ecx
004012D2   .  8B4D F0       mov     ecx, [ebp-10]
004012D5   .  E8 D0FDFFFF   call    004010AA                                    ; 调用基类的构造函数
004012DA   .  C745 FC 00000>mov     dword ptr [ebp-4], 0
004012E1   .  8B45 F0       mov     eax, [ebp-10]
004012E4   .  C700 3C204300 mov     dword ptr [eax], offset CDerived::`vftable'
004012EA   .  68 2D104000   push    0040102D
004012EF   .  68 1C204300   push    0043201C                                       ;  ASCII "I in CDerived constructor"
004012F4   .  68 40954300   push    offset std::cout
004012F9   .  E8 CAFDFFFF   call    004010C8
和以前理解的一样，不多解释

下面是析构函数(注意这里是CDerived生成的delete函数哦)

00401069   . /E9 32040000   jmp     CDerived::`scalar deleting destructor'

004014BA  |.  894D FC       mov     [ebp-4], ecx
004014BD  |.  8B4D FC       mov     ecx, [ebp-4]
004014C0  |.  E8 F9FBFFFF   call    004010BE                              ; 调用子类的析构函数
004014C5  |.  8B45 08       mov     eax, [ebp+8]
004014C8  |.  83E0 01       and     eax, 1
004014CB  |.  85C0          test    eax, eax
004014CD  |.  74 0C         je      short 004014DB
004014CF  |.  8B4D FC       mov     ecx, [ebp-4]
004014D2  |.  51            push    ecx                                            ; /Arg1
004014D3  |.  E8 A8130000   call    operator delete                                ; \operator delete

0040153F   .  894D F0       mov     [ebp-10], ecx
00401542   .  8B45 F0       mov     eax, [ebp-10]
00401545   .  C700 3C204300 mov     dword ptr [eax], offset CDerived::`vftable'
0040154B   .  C745 FC 00000>mov     dword ptr [ebp-4], 0
00401552   .  68 2D104000   push    0040102D
00401557   .  68 80204300   push    00432080                                       ;  ASCII "I in CDerived disconstructor"
0040155C   .  68 40954300   push    offset std::cout
00401561   .  E8 62FBFFFF   call    004010C8
00401566   .  83C4 08       add     esp, 8
00401569   .  8BC8          mov     ecx, eax
0040156B   .  E8 1CFBFFFF   call    0040108C
00401570   .  C745 FC FFFFF>mov     dword ptr [ebp-4], -1
00401577   .  8B4D F0       mov     ecx, [ebp-10]
0040157A   .  E8 E0FAFFFF   call    0040105F                                       ; 基类的析构函数

结论：
编译器不能自动识别析构函数，必须要多态的标识。