“输入某年某月某日，判断这一天是这一年的第几天”用c语言怎样编程

以前编过的..呵呵..

#include <stdio.h>

int isLeapYear(int year) {
return year%4==0&&year%100||year%400==0;
}
int Days(int year,int month,int day) {
int flag=isLeapYear(year);
switch(month) {
case 12: day+=30;
case 11: day+=31;
case 10: day+=30;
case 9: day+=31;
case 8: day+=31;
case 7: day+=30;
case 6: day+=31;
case 5: day+=30;
case 4: day+=31;
case 3: day+=(flag?29:28);
case 2: day+=31;
}
return day;
}

int main(int argc, char *argv[])
{
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
printf("这是这一年的第%d天\n",Days(a,b,c));
return 0;
}

#include<stdio.h>
void main()
{ int days,month,year,day,i,d;
printf("Please input(year,month,day): ");
scanf("%d,%d,%d",&year,&month,&day);
days=