含有虚继承的多继承构造函数执行顺序

#include<iostream>
using namespace std;

class Base1
{
public:
    Base1()
    {
        cout << "class Base1" << endl;
    }
};

class Base2 
{
public:
    Base2()
    {
        cout << "class Base2" << endl;
    }
};

class Level1:public Base2,virtual public Base1
{
public:
    Level1()
    {
        cout << "class Level1" << endl;
    }
};

class Level2:public Base2,virtual public Base1
{
public:
    Level2()
    {
        cout << "class Level2" << endl;
    }
};

class TopLevel:public Level1,virtual public Level2 
{
public:
    TopLevel()
    {
        cout << "class TopLevel" << endl;
    }
};

int main()
{
    TopLevel obj;   
}

执行结果 

class Base1
class Base2
class Level2
class Base2
class Level1
class TopLevel

结论：
虚基类的构造函数优先执行