(1)定义一个结构体变量(包括年,月,日).计算该日在本年中是第几天?用函数及返回值形式完成。

#include "stdio.h"
int calculate();//没传递参数
int main()
{
  printf("Please input the day(XXXX/XX/XX):\n");
  printf("\nThe day is the %dth day.\n",calculate());
}
int calculate()
{
 struct date
 {
  int year,month,day;
 } aday;
  int i,n=0; 
  scanf("%d/%d/%d",&aday.year,&aday.month,&aday.day);
  for(i=1;i  switch(i)
  { case 1:
    case 3:
    case 5:
    case 7:
    case 8:
    case 10:
    case 12:n+=31;break;
    case 4:
    case 6:
    case 9:
    case 11:n+=30;break;
    case 2:if(aday.year%4==0&&aday.year%100!=0||aday.year%400==0)
   n+=29;
       else
      n+=28;
  }
  n+=aday.day;
return n;
}