#include<iostream>
using namespace std;

class parent1
{
public:
    int a;
public:
    virtual void f()
    {

    }
};

class parent2
{
public:
    int a;
public:
    void f()
    {

    }
};
int main()
{
    cout << "sizeof(parent1) = " << sizeof(parent1) << endl; //结果为8
    cout << "sizeof(parent2) = " << sizeof(parent2) << endl; //结果为4
    return 0;
}