输入年月份，计算今天是今年的第几天？

#include<stdio.h>  void main()  {      int year,month,day,days,i,d;      printf("请输入年，月，日：\n");      scanf("%d,%d,%d",&year,&month,&day);      days=0;      for(i=1;i<month;i++)      {          switch(i)          {              case 1:              case 3:              case 5:              case 7:              case 8:              case 10:              case 12:d=31;break;              case 4:              case 6:              case 9:              case 11:d=30;break;              case 2:if(year%4==0&&year%100!=0||year%400==0)                         d=29;                     else d=28;          }          days+=d;      }      printf("%d年%d月%d日是这一年的第%d天。\n",year,month,day,days+day);  }

运行结果：