//GCC编译器--单个虚拟继承.cpp
//2010.8.18
//虚基类表到底是那个？，还是说派生类的虚函数表的上边和下边都是？
//GCC编译器
#include <iostream>
using   namespace std;
//
class Base
{public:Base(int a = 10):a(a){cout << "Base::Base()" << endl;}virtual void show1(){cout << "Base::show1()" << endl;cout << a << endl;}private:int a;
};
//
class Derived : virtual public Base
{public:Derived(int b = 100):b(b){cout << "Derived::derived()" << endl;}virtual void show2(){cout << "Derived::show2()" << endl;cout << b << endl;}private:int b;
};
//
int main()
{Derived obj;int** p = (int**)&obj;cout << "虚拟继承了基类的派生类的对象内存布局：" <<endl;for (int i = 0; i != sizeof(obj)/4; ++i){cout << p[i] << endl;}typedef void (*fun)(void*pThis);//this指针非常重要cout << endl << "第一虚函数表第一项，虚函数Derived::show2()地址：" << (int*)p[0][0] << endl;((fun)(p[0][0]))(p);cout << "第二虚函数表第一项，虚函数Base::show1()地址   ：" << (int*)p[2][0] << endl;((fun)(p[2][0]))(p+2);cout << endl << "派生类虚函数表指针往低地址方向寻址：" << endl;cout << "p[0][-1] = " << (int*)p[0][-1] << endl;cout << "p[0][-2] = " << (int*)p[0][-2] << endl;cout << "p[0][-3] = " << (int*)p[0][-3] << endl;cout << endl << "派生类虚函数表指针往高地址方向寻址：" << endl;cout << "p[0][0] = " << (int*)p[0][0] << "(这个是show2()函数地址)" << endl;cout << "p[0][1] = " << (int*)p[0][1] << endl;cout << "p[0][2] = " << (int*)p[0][2] << endl;cout << "p[0][3] = " << (int*)p[0][3] << endl;cout << endl << "是否往高方向寻找和往地方向寻找所找到的都是虚基类表呢？" << endl;//system("pause");return 0;
}
/*
Base::Base()
Derived::derived()
虚拟继承了基类的派生类的对象内存布局：
0x472d4c
0x64
0x472d5c
0xa第一虚函数表第一项，虚函数Derived::show2()地址：0x41cd50
Derived::show2()
100
第二虚函数表第一项，虚函数Base::show1()地址   ：0x41ccbc
Base::show1()
10派生类虚函数表指针往低地址方向寻址：
p[0][-1] = 0x471388
p[0][-2] = 0
p[0][-3] = 0x8派生类虚函数表指针往高地址方向寻址：
p[0][0] = 0x41cd50(这个是show2()函数地址)
p[0][1] = 0
p[0][2] = 0xfffffff8
p[0][3] = 0x471388是否往高方向寻找和往地方向寻找所找到的都是虚基类表呢？
*/