测试虚函数表并通过指针调用虚函数表的真实函数

[c++]代码库

#include <iostream>
#include <stdio.h>
typedef void (*fun_pointer)(void);

using namespace std;
class Test
{
 public:
   Test()
       {
     cout<<"Test()."<<endl;
    }
   virtual void print()
       {
     cout<<"Test::Virtual void print1()."<<endl;
    }
   virtual void print2()
       {
     cout<<"Test::virtual void print2()."<<endl;
    }
};

class TestDrived:public Test
{
 public:
 static int var;
  TestDrived()
    {
     cout<<"TestDrived()."<<endl;
    }
  virtual void print()
    {
       cout<<"TestDrived::virtual void print1()."<<endl;
    }
  virtual void print2()
    {
    cout<<"TestDrived::virtual void print2()."<<endl;
    }
  void GetVtblAddress()
    {
         cout<<"vtbl address:"<<(int*)this<<endl;
    }
  void GetFirstVtblFunctionAddress()
    {
    cout<<"First vbtl funtion address:"<<(int*)*(int*)this+0 << endl;
    }
  void GetSecondVtblFunctionAddress()
    {
    cout<<"Second vbtl funtion address:"<<(int*)*(int*)this+1 << endl;
    }
  void CallFirstVtblFunction()
    {
    fun = (fun_pointer)* ( (int*) *(int*)this+0 );
     cout<<"CallFirstVbtlFunction:"<<endl;
     fun();
    }
  void CallSecondVtblFunction()
    {
    fun = (fun_pointer)* ( (int*) *(int*)this+1 );
     cout<<"CallSecondVbtlFunction:"<<endl;
     fun();
    }
private:
    fun_pointer fun;
};


int TestDrived::var = 3;

int main()
{
 cout<<"sizeof(int):"<<sizeof(int)<<"sizeof(int*)"<<sizeof(int*)<<endl;
 fun_pointer fun = NULL;
 TestDrived a;
 a.GetVtblAddress();
 cout<<"The var's address is:"<<&TestDrived::var<<endl;
 a.GetFirstVtblFunctionAddress();
 a.GetSecondVtblFunctionAddress();
 a.CallFirstVtblFunction();
 a.CallSecondVtblFunction();
 return 0;
}