[C++知识库]18.1C++ 多态的原理，虚函数表的覆盖

普通类的大小

#include<iostream>
using namespace std;

class Father
{
private:
    int data;
public:
    Father(int i):data(i){};
    ~Father();
public:
    void show()
    {
        cout << "this is father class" << endl;
    }
};

int main()
{
    cout<<sizeof(Father)<<endl;  
    return 0;
}

/*
[root@Orz 18:36 ~]# run
4
[root@Orz 18:36 ~]# 

*/

带virtual函数类的大小

#include<iostream>
using namespace std;

class Father
{
private:
    int data;
public:
    Father(int i):data(i){};
    ~Father();
public:
    virtual void show()
    {
        cout << "this is father class" << endl;
    }
};

int main()
{
    cout<<sizeof(Father)<<endl;  
    return 0;
}

[root@Orz 18:36 ~]# run
16
[root@Orz 18:36 ~]# 

?一下大了这么多，什么原因