C++虚函数表的验证

要了解C++对象的虚函数的内存布局，推荐的是如下的三篇由浅入深的文章：

C++虚函数表解析

http://blog.youkuaiyun.com/haoel/article/details/1948051

C++对象的内存布局（上）

http://blog.youkuaiyun.com/haoel/article/details/3081328

C++对象的内存布局（下）

http://blog.youkuaiyun.com/haoel/article/details/3081385

作为“课后作业”，在64位linux上写了一个验证代码 （g++ (GCC) 4.4.6）：

#include <iostream>
using namespace std;

class Base
{
	virtual void foo1(){cout<<"Base::foo1"<<endl;}
	virtual void foo2(){cout<<"Base::foo2"<<endl;}
	virtual void foo3(){cout<<"Base::foo3"<<endl;}
};

class Derive1: public Base
{
	virtual void foo1(){cout<<"Derive1::foo1"<<endl;}
	virtual void fooDerive1(){cout<<"Derive1::fooDerive"<<endl;}
};

class Derive2: public Base
{
	virtual void foo1(){cout<<"Derive2::foo1"<<endl;}
	virtual void fooDerive2(){cout<<"Derive2::fooDerive"<<endl;}
};

class Derive3 : public Derive1, public Derive2
{
	virtual void foo1(){cout<<"Derive3::foo1"<<endl;}
	virtual void fooDerive3(){cout<<"Derive3::fooDerive3"<<endl;}
};

typedef void(*Fun)(void);

main()
{	
	Derive3 d3;
	
	long long** pVtab = (long long**)&d3;
	Fun pFun = NULL;

	for(int i=0; i<5; i++)
	{
		pFun = (Fun)pVtab[0][i];
		cout<<"["<<i<<"]";
		pFun();
	}
	
	cout<<"--------------"<<endl;
	
	for(int i=0; (Fun)pVtab[1][i]!=NULL; i++)
	{
		pFun = (Fun)pVtab[1][i];
		cout<<"["<<i<<"]";
		pFun();
	}
}

执行结果：

[0]Derive3::foo1
[1]Base::foo2
[2]Base::foo3
[3]Derive1::fooDerive
[4]Derive3::fooDerive3
--------------
[0]Derive3::foo1
[1]Base::foo2
[2]Base::foo3
[3]Derive2::fooDerive

如果是单线的继承，内存的排布跟文章中介绍都一样。

如果是菱形继承、虚拟继承、多重集成， 还是有些区别，第一个虚表最后有一个未知节点，不是直接为0结束，不知道要怎么分析下去这块内存的指向了 :(