请高手帮忙看看，有错误不知哪里错了，谢谢。
#include <stdio.h>
int is_leap_year(int year)
{
  int leap;
  if(year%4==0&&year%100!=0||year%400==0)leap=1;
  else leap=0;
  return leap;
}
int len_of_month(int year,int month)
{
  int month_days;
  if(month==2)
    if(is_leap_year(year))month_days=29;
    else month_days=28;
  else if(month==4||month==6||month==9||month==11)month_days=30;
       else month_days=31;
  return month_days;
}
int len_of_days(int year,int month,int date)
{
  int total_days,n;
  for(n=1,total_days=0;n<month;n++)
     total_days+=len_of_month(year,n);
  total_days+=date;
  return total_days;
}
void main()
{
  int year1,month1,date1,days1,year2,month2,date2,days2,days3,days,n;
  printf("Please input year1,month1,date1:");
  scanf("%d,%d,%d",&year1,&month1,&date1);
  printf("Please input year2,month2,date2:");
  scanf("%d,%d,%d",&year2,&month2,&date2);
  days1=len_of_days(year1,month1,date1);
  days2=len_of_days(year2,month2,date2);
  for(n=year1,days3=0;n<year2;n++)
  {
    days3+=(is_leap_year(year1)?366:365);
  }
  days=days3+days2-days1;
  printf("%d/%d/%d~%d/%d/%d is the %d Day\n",year1,month1,date1,year2,month2,date2,days);
  getch();
  return 0;
}