Question

c语言输入某年某月某日 判断这一天是这一年的第几天用switch

Answer 1

#include "stdio.h"
#include "conio.h"
int main()
{
	int day,month,year,sum,leap;
	printf("\nplease input year,month,day\n");
	scanf("%d,%d,%d",&year,&month,&day);
	switch(month) /*先计算某月以前月份的总天数*/
	{
	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+day; /*再加上某天的天数*/
	if(year%400==0||(year%4==0&&year%100!=0)) /*判断是不是闰年*/
		leap=1;
	else
		leap=0;
	if(leap==1&&month>2) /*如果是闰年且月份大于2,总天数应该加一天*/
		sum++;
	printf("It is the %dth day.",sum);
	getchar(); 
}

Answer 2

参考代码如下：
#include <stdio.h>

int main()
{
int i, days = 0;
int year, month, day;
int day_tab[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
printf("输入年、月、日，用空格隔开：");
scanf("%d%d%d", &year, &month, &day);
for (i=1; i<month; i++)
{
days += day_tab[i];
}
days += day;
if ((year%4==0 && year%100!=0 || year%400==0) && month>=3)
days+=1;
printf("%d年%d月%d日是这一年的第%d天！\n", year, month, day, days);
return 0;
}

Answer 3

void isleap(int n)
{
if(n%400==0||n%100!=&&n%4==0)

return 1;

return 0;

}

scanf("%d%d%d",&year,&month,&day);
int result=day;
switch（month）

{
case 12:result+=30;
case 11:result+=31;
case 10:result+=30;
case 9:result+=31;
case 8:result+=30;
case 7:result+=31;
case 6:result+=31;
case 5:result+=30;
case 4:result+=31;
case 3:if(isleap(year)){result+=29;}else {result+=28;}
case 2:result+=31;
}
printf("%d\n",result);
核心代码，另外自己补充吧