定义一个结构体变量，给定年月日确定这一天是一年中的第几天，（考虑闰年问题）

 1 //定义一个结构体变量，给定年月日确定这一天是一年中的第几天，（考虑闰年问题）
 2 #include<stdio.h>
 3 struct
 4 {
 5     int year;
 6     int month;
 7     int day;
 8 }date;
 9 
10 int main()
11 {
12     int days;
13     printf("input year,month,day:
");
14     scanf("%d,%d,%d", &date.year, &date.month, &date.day);
15     switch (date.month)
16     {
17     case 1:days = date.day; break;
18     case 2:days = date.day + 31; break;
19     case 3:days = date.day + 59; break;
20     case 4:days = date.day + 90; break;
21     case 5:days = date.day + 120; break;
22     case 6:days = date.day + 151; break;
23     case 7:days = date.day + 181; break;
24     case 8:days = date.day + 212; break;
25     case 9:days = date.day + 243; break;
26     case 10:days = date.day + 273; break;
27     case 11:days = date.day + 304; break;
28     case 12:days = date.day + 334; break;
29     }
30     if((date.year % 4 == 0 && date.year % 100 != 0 
31         || date.year % 400 == 0) && date.month >=3)
32         days += 1;
33     printf("%d",days);
34     return 0;
35 }