8 算某年某日是某年的第多少天 看似很多，其实都是很简单的判断语句，要有耐心。 Case尽量另起一行更好看，打一段书写一段运行一段 虽然慢但很有感觉
{//五花括号{}没有这个就会报错 语法错误 大括号代表的就是你的内容
int year,month,day;
int sum = 0; int leap = 0;
printf("请输入年月日:");
scanf_s("%d,%d,%d",&year,&month,&day);
printf("year=%d month=%d day=%d\n",year,month,day);
switch (month) //()括号里的数字代表下面case几
//需要你自行判断需要几个，多了也没事
case 1:
printf("一月份\n");
sum = 0;
break;
case 2:
printf("二月份\n");
sum = 31;
break;
case 3:
printf("三月份\n");
sum = 59;
break;
case 4:
printf("四月份\n");
sum = 90;
break;
case 5:
printf("五月份\n");
sum = 120;
break;
case 6:
printf("六月份\n");
sum = 151;
break;
case 7:
printf("七月份\n");
sum = 181;
break;

case 9:
printf("九月份\n");
sum = 242;
break;
case 10:
printf("十月份\n");
sum = 273;
break;
case 11:
printf("十一月份\n");
sum = 303;
break;
case 12:
printf("一月份\n");
sum = 334;
break;
}
if (year % 400 == 0 || (year%100==0&&year%4!= 0))
{
leap = 1;
}
else
{
leap = 0;
}
if (leap == 1 && month > 2)//&&且 ||或 ！非 ！||&& 依次顺序
{
sum++;
}
sum = sum + leap;