C语言从键盘上输入年份和月份，计算并输出这一年的这一月共有多少天。

#include<stdio.h>

void main()

{

 int y, n, s = 0;//定义变量

 scanf_s("%d-%d", &y, &n);//输入年月

 switch (n)//根据月份判断天数

 {

 case 1:s = 31; break;

 case 2:s = 28; break;

 case 3:s = 31; break;

 case 4:s = 30; break;

 case 5:s = 31; break;

 case 6:s = 30; break;

 case 7:s = 31; break;

 case 8:s = 31; break;

 case 9:s = 30; break;

 case 10:s = 31; break;

 case 11:s = 30; break;

 case 12:s = 31; break;

 }

 if (n == 2)//判断闰年2月差异

 {

 if (y % 4 == 0 && y % 100 != 0 || y % 400 == 0)

 s = 29;

 else

 s = 28;

 }

 printf("%d\n", s);

}