c#判断输入是否为数字

```#include int main() {int year, month, day;printf("请输入年月日，格式为YYYY-MM-DD：");scanf("%d-%d-%d", &year, &month, &day);int days[] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 }; // 存储每个月的天数int sum = 0;for (int i = 1; i 2) {sum += 1;}}// 计算该日期是星期...