【c语言】输入某年某月 输出该月有几天

//输入某年某月 输出该月有几天
#include <>
int main() {
	int year, month, days;                 //定义year,month,days
	printf("输入某年某月:");
	scanf("%d %d", &year, &month);         //输入年份,月份
	switch (month) {                       //运用switch...case...用法
		case 1:
		case 3:
		case 5:
		case 7:
		case 8:
		case 10:
		case 12:
			days = 31;
			break;
		case 4:
		case 6:
		case 9:
		case 11:
			days = 30;
			break;
		case 2:
			if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)   //判断平年还是闰年
				days = 29;
			else
				days = 28;
			break;
	}
	printf("%d年的%d月有%d天", year, month, days);   //输出该月的天数
}