输入年月日，输出该日期是当年的第几天

 1 //给定一个日期,求该日期是该年的多少天？
 2 #include <stdio.h>
 3 #include <stdlib.h>
 4 
 5 int main(int argc, char *argv[])
 6 {
 7     int y, m, d, n = 0, i, res;
 8     int months[13] = {0,31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
 9 
10     while (fflush(stdin), (res = scanf("%d%d%d", &y, &m, &d)) != EOF)
11     {
12         if (res != 3) 
13         {
14             printf("Error!\n");
15             continue;
16         }
17         n = 0;
18         if(( y % 4 == 0 && y % 100 != 0) || y % 400 == 0)
19             months[2] = 29;
20         else 
21             months[2] = 28;
22         for ( i = 1; i < m; i++)
23             n += months[i];
24         n += d;
25         printf("该日期是该年的%d天.\n", n);
26     }
27     system("pause");
28     return 0;
29 }