时间计算器

int YEAR;
int monthday(int mon)
{int d;
 while(mon>0)
 {if (mon==1||mon==3||mon==5||mon==7||mon==8||mon==10||mon==12)
  d=31;
  else
   if (mon==2)
    {if (YEAR%4==0&&YEAR%100!=0||YEAR%400==0)
     d=29;
     else
     d=28;
    }
   else
   d=30;
   return d;
 }
}
main()
{int month,day,day1,day2,i,s;
 day2=0;
 printf("input a date:\n");
 scanf("%d-%d-%d",&YEAR,&month,&day);
 day1=monthday(month);
 if (day>day1)
  printf("the date is error!\n");
 else
  {for (i=1;i<month;i++)
   {day1=monthday(i);
    day2=day2+day1;}