警告：枚举类型未设定范围

#include<iostream>
using namespace std;
int main(void)
{
    enum Week{ Sunday, Monday, Tuesday};
    Week week;
    int i;
    for (i = 0; i < 3; i++)
    {
        switch (i)
        {
            case 0:week = Week(0); break;
            case 1:week = Week(1); break;
            case 2:week = Week(2); break;
        }
        switch(week)
        {
            case Sunday:cout<<"Sunday"<<endl; break;
            case Monday:cout<<"Monday"<<endl; break;
            case Tuesday:cout<<"Tuesday"<<endl; break;
        }
    }
        return 0;
}