打印C++对象的virtual table

csdn看到一帖讨论virtual table，我不是太了解，稍微翻了点资料，原来C++对象的前4字节是指向vitural table 的指针。

于是尝试写一个打印vitural table 的函数，还挺管用

 

 

Example Source Code [http://www.cnblogs.com/tomsheep/]

#include <iostream>
using namespace std;

class A
{
public:
    virtual void f1()
    {
        cout<<"A::f1()"<<endl;
    }
};
class B :public A
{
public:
    virtual void f2()
    {
        cout<<"B::f1()"<<endl;
    }
};
class C : public B
{
public:
    virtual void f2()
    {
        cout<<"C::f2()"<<endl;
    }
};




void dump_vtable(const int *pObj){
    typedef void (*pFun)();
    int * const &pVTable = (int *)(*pObj);
    cout<<"VTable: 0x"<<hex<<*pVTable<<endl;
    void *pVoid = NULL;
    pFun fun;
    int i = 0;
    while(pVoid = (int *)(*(pVTable + i))){
        fun = (pFun)pVoid;
        cout<<"func["<<i<<"]: address "<<(int *)(*(pVTable + i))<<"  call..."<<endl;
        fun();
        ++i;
    }
}

int main(int argc, char* argv[])
{
    B b;
    int *pb = (int *)(&b);
    dump_vtable(pb);
    return 0;
}

 

另外，如果对象没有virtual函数，就不会有virtual table，对象直接从成员开始

Example Source Code [http://www.cnblogs.com/tomsheep/]

class D{
public:
    int a;
    D():a(222){
    }
};

int main(int argc, char* argv[])
{
    D d;
    int *pd = (int *)(&d);
    cout<<hex<<pd<<" value:"<<dec<<(*pd);
    return 0;
}