#include<stdio.h>struct date{int year;int month;int day;}date;void main(){int sum=0,leap;printf("\n請輸入日期（年,月,日）\n");scanf("%d,%d,%d",&date.year,&date.month,&date.day);switch(date.month)//先計算某月以前月份的總天數。{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("data error");break;}sum=sum+date.day;//再加上某天的天數。if(date.year%400==0||(date.year%4==0&&date.year%100!=0))leap=1;elseleap=0;if(leap==1&&date.month>2)//如果是閏年且月份大於2,總天數應該加一天。sum++;printf("這天是當年的第 %d 天。\n",sum);}