看c++程序

给你修改了一下：
#include <iostream>
using namespace std;
int dayfun (int nowyear,int nowmonth,int nowday)
{
bool isrunnian=(((nowyear%4==0)&&(nowyear%100!=0))||(nowyear%400==0));
int whichday=0;
for (int i=1;i<nowmonth;i++)
{
switch(i){
case 1: case 3: case 5: case 7: case 8: case 10: case 12:
{whichday+=31;break;}
case 4: case 6:case 9: case 11:
{whichday+=30;break;}
case 2:
if(isrunnian==true)
{whichday+=29;break;}
else
{whichday+=28;break;}
}
}
return whichday+nowday;
}

int main()
{
int nowyear,nowmonth,nowday,ff=0;
cout<<"input a date:"<<endl;
cout <<"year=";
cin>>nowyear;
cout<<"month=";
cin>>nowmonth;
cout<<"day=";
cin>>nowday;
ff=dayfun(nowyear,nowm