//题目：输入某年某月某日，判断这一天是这一年的第几天？程序分析：以3月5日为例，应该先把前两个月的加起来，然后再加上5天即本年的第几天，特殊情况，闰年且输入月份大于3时需考虑多加一天。
include <stdio.h>
int main()
{
int year, month, day, sum = 0, leap;
printf("输入年月日，格式为年，月，日如1986,04,05\n");
scanf("%d,%d,%d", &year, &month, &day);
switch (month)
{
case 1:
sum = 0;
break;
case 2:
sum = 31;
break;
case 3:
sum = 59;
break;
case 4:
sum = 90;
break;
case 5:
sum = 120;
break;
case 6:
sum = 151;
break;
case 7:
sum = 181;
break;
case 8:
sum = 212;
break;
case 9:
sum = 243;
break;
case 10:
sum = 273;
break;
case 11:
sum = 304;
break;
case 12:
sum = 334;
break;
default:
printf("error");
break;
}
sum = sum + day;
if ((year % 4 == 0) || (year % 400 == 0 && year % 4 != 0))
{
leap = 1;
}
else
{
leap = 0;
}
if (leap == 1 && month > 2)
{
sum++;
}
printf("这是这一年的第%d天.\n", sum);
}
