这应该这么加上去啊?

#include <stdio.h>
int main()
{
int y = 0;
int m = 0;
int days[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
while (~scanf("%d%d", &y, &m))
{
int day = days[m - 1];
if ((y % 4 == 0 && y % 100 != 0) || (y % 400 == 0))
{
if (m == 2)
day++;
}
printf("%d\n", day);
}
return 0;
}

修改如下，供参考：

#include <stdio.h>
int main()
{
    int y = 0;
    int m = 0;
    int days[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
    while (scanf("%d%d", &y, &m)==2 && y!=0 && m!=0)//输入 0  0 结束输入
    {
        if(m%12==0) m=12;
        else        m=m%12;
        int day = days[m - 1];
        if ((m == 2)&& (y % 4 == 0 && y % 100 != 0) || (y % 400 == 0))
        {
            //if (m == 2)
            day++;
        }
        printf("days:%d\n", day);
    }
    return 0;
}