C语言经典编程题（04）

设计一个程序使输入某年某月某日，能判断这一天是这一年的第几天？

#include
int main()
{
	int year,month,day,num=0;
	printf("分别输入输入年月日:");
	scanf("%d %d %d",&year,&month,&day);
	switch(month)
	{
		case 1: num=0;                      break;
		case 2: num=31;                      break;
		case 3: num=31+28;                      break;
		case 4: num=31+28+31;                      break;
		case 5: num=31+28+31+30;                      break;
		case 6: num=31+28+31+30+31;                      break;
		case 7: num=31+28+31+30+31+30;                      break;
		case 8: num=31+28+31+30+31+30+31;                      break;
		case 9: num=31+28+31+30+31+30+31+31;                      break;
		case 10: num=31+28+31+30+31+30+31+31+30;                      break;
		case 11: num=31+28+31+30+31+30+31+31+30+31;                      break;
		case 12: num=31+28+31+30+31+30+31+31+30+31+30;                      break;
	}
	num=num+day;
	if(year%4==0&&year%100!=0||year%400==0)
	{
		if(month>2)
		num++;
	 } 
	 printf("%d年%d月%d日是今年的第%d天",year,month,day,num);
	return 0;
 }