含有虚函数的类sizeof大小

#include <iostream>

using namespace std;
class Base1{

    virtual void fun1(){}

    virtual void fun11(){}

public:

    virtual ~Base1();

};

class Base2{

    virtual void fun2(){}

};

class DerivedFromOne: public Base2

{
    virtual void fun2(){}

    virtual void fun22(){}

};

class DerivedFromTwo: public Base1, public Base2
{
    virtual void fun3(){}
};
void main()

{
    cout << "sizeof Base1 " << sizeof(Base1) << endl;
    cout << "sizeof Base1 " << sizeof(Base2) << endl;
    cout << "sizeof FromOne " << sizeof(DerivedFromOne) << endl;
    cout << "sizeof FromTwo " << sizeof(DerivedFromTwo) << endl;
    getchar();
}