c语言求一年中的多少天

#include
int main()
{
	int year, month, day;
	int IsLeapYear();
	int IsDays();
	int sum = IsDays(year,month,day);
	printf("%d", sum);
}
int  IsLeapYear(int year) { //判断闰年
	if ((year % 4 == 0 && year % 100 != 0) ||year%400==0) {
		return 	 29;   //闰年
	}
	else
	return	28;	//不是闰年
}
int IsDays(int year, int month, int day) { //第多少天
	scanf_s("%d,%d,%d", &year, &month, &day);
	if (IsLeapYear(year) == 29) {  //闰年
		switch (month) {
		case 1:month=0; break;
		case 2:month=31; break;
		case 3:month=60; break;
		case 4:month=91; break;
		case 5:month=121; break;
		case 6:month = 152; break;
		case 7:month = 182; break;
		case 8:month = 213; break;
		case 9:month = 244; break;
		case 10:month = 274; break;
		case 11:month = 305; break;
		case 12:month = 335; break;
		default:printf("输入的月份有误！");
		}
		return month + day;
	}
	else {
		switch (month) { //不是闰年
		case 1:month = 0; break;
		case 2:month = 31; break;
		case 3:month = 59; break;
		case 4:month = 90; break;
		case 5:month = 120; break;
		case 6:month = 151; break;
		case 7:month = 181; break;
		case 8:month = 212; break;
		case 9:month = 243; break;
		case 10:month = 273; break;
		case 11:month = 304; break;
		case 12:month = 334;break;
		default:printf("输入的月份有误！");
		}
		return month + day;
	}
}