输入年月 输出该月天数（C语言）

#include<stdio.h>int main(){int year,month,days;printf("请输入年，月：");scanf("%d %d",&year,&month);if(month<1||month>13) {printf("数据不合法！！\n"); }else{switch(month){case 1:days=31;break;case 2:if(year%4==0&&year%100!=0||year%400==0)days=29;elsedays=28;break;case 3:days=31;break;case 4:days=30;break;case 5:days=31;break;case 6:days=30;break;case 7:days=31;break;case 8:days=31;break;case 9:days=30;break;case 10:days=31;break;case 11:days=30;break;case 12:days=31;break;}printf("%d年%d月有%d天\n",year,month,days);}return 0;}