第11周项目5 当年第几天

#include <iostream>
using namespace std;
int days(int y,int m,int d);
int main()
{
int year,mouth,day;
cout<<"请输入年，月，日"<<endl;
cin>>year>>mouth>>day;
if (mouth>12||day>31)
cout<<"输入错误，请重试！"<<endl;
else
cout<<"这是这一年的第"<<days(year,mouth,day)<<"天。"<<endl;
return 0;
}
int days (int y,int m,int d)
{
int g=31,h=30,i,j;
if (y%4==0&&y%100!=0||y%400==0)
i=29;
else
i=28;
switch (m)
{case 1:j=d;break;
case 2:j=g+d;break;
case 3:j=g+i+d;break;
case 4:j=2*g+i+d;break;
case 5:j=2*g+i+h+d;break;
case 6:j=3*g+i+h+d;break;
case 7:j=3*g+i+2*h+d;break;
case 8:j=4*g+i+2*h+d;break;
case 9:j=5*g+i+2*h+d;break;
case 10:j=5*g+i+3*h+d;break;
case 11:j=6*g+i+3*h+d;break;
case 12:j=6*g+i+4*h+d;break;}
return j;
}