根据用户输入年和月份值，输出对应月份的天数。

#include <stdio.h>
int main()
{
int year,month,days,flag=1;
printf("请输入年份和月份：");
scanf("%d,%d",&year,&month);
switch(month)
{
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)
days=29;
else
days=28;
default:
flag=0;
}
if(flag=0)
printf("月份值输入错误！\n");
else
printf("%d年%d月有%d天！\n",year,month,days);
return 0;
}