c++ 子类父类 的构造函数调用顺序

#include<iostream>
#include<cstdio>

using namespace std;

class parent{
public:
int a,b;
parent()
{
a=b=0;
printf("parent:a=%d,b=%d\n",a,b);
}
~parent()
{
printf("parent out\n");
}
};

class son:parent
{
public:
int a,b;
son()
{
a=b=1;
printf("son:a=%d,b=%d\n",a,b);
}
~son()
{
printf("son out\n");
}
};

int main()
{
son test;
return 0;
}