下面是在下的代码:
#include <iostream>
using namespace std;
class Point
{
private:
int X;
int Y;
public:
Point() {}
Point(int x, int y) : X(x), Y(y) {}
const int getX() { return X; }
const int getY() { return Y; }
virtual ~Point() {}
virtual void printX() { cout << "X=" << X << endl; }
virtual void printY() { cout << "Y=" << Y << endl; }
};
class Point3D :public Point
{
private:
int Z;
public:
Point3D()
:Point()
{}
Point3D(int x, int y, int z)
:Point(x, y), Z(z)
{}
const int getZ() { return Z; }
virtual ~Point3D() {}
virtual void printZ() { cout << "Z=" << Z << endl; }
virtual void fun() { cout << "fun" << endl; }
};
int main()
{
typedef void(*Funptr)();
Point point(1, 2);
Point3D point3D(1, 2, 3);
Point3D* p3D = &point3D;
void*** _p3D = (void***)&point3D;
void** vfptr3D = *_p3D;
int** ptr3D = (int**)vfptr3D;
while (*ptr3D != NULL)
{
cout << *ptr3D << endl;
ptr3D++;
}
cout << "--------------------------" << endl;
Point* p = &point;
void*** _p = (void***)&point;
void** vfptr = *_p;
int** ptr = (int**)vfptr;
while (*ptr != NULL)
{
cout << *ptr << endl;
ptr++;
}
return 0;
}
在上面的代码中,在下打印了派生类和基类的虚函数表,结果如下
按理说,基类的虚函数表只有三项,分别对应~point(),printX(),printY(),如下图
但大家也发现了,打印出的结果中最后多了一项!这是在VS2015下的结果,如果在codeblocks12.11下,连派生类的虚函数表最后也会多出一项,如下
但是,只要去掉虚析构函数,就不会出现意料之外的多余项,可见出现多余项与类中含有虚析构函数有关,但在下又想不明白这是为什么,所以特向大家请教,希望各路大神能够不吝赐教,在下先行谢过!