关于虚拟继承类的大小问题探索，VC++ 和 G++ 结果是有区别的

#include <stdio.h>
#include<stdlib.h>
#include<iostream>
using namespace std;

#define DWORD unsigned long
class A
    {
    public:
        int x;
        int y;
        A()
            {
            x = 1;
            y = 2;
            };
        void go()
            {
            printf("A go()\n");
            }
        virtual void move()
            {
            printf ("A Move()\n");
            }
    };

class  B: virtual public A
    {
    public:
        int x;
        int y;
        B()
            {
            x = 3;
            y = 4;
            }
        void go()
            {
            printf("B go()\n");
            }
        virtual void move()
            {
            printf ("B Move()\n");
            }
        virtual void move2()
            {
            printf ("B Move2()\n");
            }
    };

class C: public A
    {
    public:
        int x;
        int y;
        C()
            {
            x = 5;
            y = 6;
            }
        /*
        virtual void move()
        {
         printf ("C Move()\n");
        }
        virtual void move3()
        {
         printf ("C Move2()\n");
        }
        */
    };

class D:virtual public C,virtual public B
    {

    };

void PrintClass(void * Base,int size)
    {
    //打印结构体系
    DWORD  p, pNext;
    printf("--------size= %d------------------\n",size);
    for(int i = 0; i<size/4; i++)
            {
            p = (DWORD)Base+i*4;
            pNext = *(DWORD *)(p);
            printf("   |--0x%08x    :    0x%08x ",p,pNext);  //打印类里都是些什么东西
            if(pNext>0x400000)  //打印一下此地址下的连续三个地址的内容
                    {
                    printf("  :0x%08x 0x%08x 0x%08x",*(DWORD *)pNext,*(DWORD *)(pNext+4),*(DWORD *)(pNext+8));
                    }
            printf("\n");
            }
    printf("   |--End \n\n");
    }

int main(int argc, char* argv[])
    {
    void * p1,*p2,*p3,*p4;
    D dd;   //因为它继承了所有，所以用它做测试
    B * boy = &dd;   //都是父类
    C * child = &dd;

    A * Man = boy;

    int sizeA = sizeof(A);
    int sizeB = sizeof(B);
    int sizeC = sizeof(C);
    int sizeD = sizeof(D);
    //转化成指针

    p1 = (void *)Man;
    p2 = (void *)boy;
    p3 = (void *)child;
    p4 = (void *)&dd;


    typedef void (*VFun)();
    B aa;
    int **vPtr=(int**)&aa;
    cout<<"B first virtual table address : "<<vPtr[0]<<endl;
    cout<<"B::move address : "<<(int*)vPtr[0][0]<<endl;
    VFun pVF=VFun(vPtr[0][0]);
    pVF();
    cout<<"B move2 address : "<<(int*)vPtr[0][1]<<endl;
    pVF=VFun(vPtr[0][1]);
    pVF();
    cout<<"B end address : "<<(int*)vPtr[0][2]<<endl;
    cout<<vPtr[0][2]<<endl;
    cout<<"B member1 "<<vPtr[1]<<endl;
    cout<<"B member2 "<<vPtr[2]<<endl;
     cout<<"B second virtual table address : "<<vPtr[3]<<endl;
    cout<<"A move address : "<<(int*)vPtr[3][0]<<endl;
    pVF=VFun(vPtr[3][0]);
    pVF();
    cout<<"A end address : "<<(int*)vPtr[3][1]<<endl;
    cout<<vPtr[3][1]<<endl;

    C cc;
    vPtr=(int**)&cc;
    cout<<"C first virtual table address : "<<vPtr[0]<<endl;
    cout<<"A::move address : "<<(int*)vPtr[0][0]<<endl;
    pVF=VFun(vPtr[0][0]);
    pVF();
    cout<<"A end address : "<<(int*)vPtr[0][1]<<endl;
    cout<<vPtr[0][1]<<endl;

    vPtr=(int**)&dd;
    cout<<"D first virtual table address : "<<vPtr[0]<<endl;
    cout<<"D end address : "<<(int*)vPtr[0][0]<<endl;
    cout<<vPtr[0][0]<<endl;
    cout<<"D end address : "<<(int*)vPtr[0][1]<<endl;
    cout<<vPtr[0][1]<<endl;

    cout<<"D second virtual table address : "<<vPtr[1]<<endl;
    cout<<"C::move address : "<<(int*)vPtr[1][0]<<endl;
    pVF=VFun(vPtr[1][0]);
    pVF();
    cout<<"C end address : "<<(int*)vPtr[1][1]<<endl;
    cout<<vPtr[1][1]<<endl;

    cout<<"D member1 "<<vPtr[2]<<endl;
    cout<<"D member2 "<<vPtr[3]<<endl;
    cout<<"D member3 "<<vPtr[4]<<endl;
    cout<<"D member4 "<<vPtr[5]<<endl;

    cout<<"D third virtual table address : "<<vPtr[6]<<endl;
    cout<<"B::move address : "<<(int*)vPtr[6][0]<<endl;
    pVF=VFun(vPtr[6][0]);
    pVF();
    cout<<"B::move address : "<<(int*)vPtr[6][1]<<endl;
    pVF=VFun(vPtr[6][1]);
    pVF();
    cout<<"B end address : "<<(int*)vPtr[6][2]<<endl;
    cout<<vPtr[6][2]<<endl;

    cout<<"B member1 "<<vPtr[7]<<endl;
    cout<<"B member2 "<<vPtr[8]<<endl;

    cout<<"D four virtual table address : "<<vPtr[9]<<endl;
    cout<<"A::move address : "<<(int*)vPtr[9][0]<<endl;
    pVF=VFun(vPtr[9][0]);
    pVF();
    cout<<"A end address : "<<(int*)vPtr[9][1]<<endl;
    cout<<vPtr[9][1]<<endl;

    cout<<"A member1 "<<vPtr[10]<<endl;
    cout<<"A member2 "<<vPtr[11]<<endl;


    PrintClass(p1,sizeA);
    PrintClass(p2,sizeB);
    PrintClass(p3,sizeC);
    PrintClass(p4,sizeD);

    system("pause");

    return 0;
    }