关于计算输入某年某月某日，并算出这是一年中的第几天的问题
是这样的，源程序是这个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);}
但是我感觉这个程序还是有漏洞的，假如日期不再范围之内怎么办？所以我自己“改良”了一下，就成了这个样子
#include<stdio.h>
main()
{
int year,month,day,sum,i;
printf("请输入日期：年，月，日");
scanf("%d,%d,%d",&year,&month,&day);
switch(month)
{
case 1:sum=0;if(day>31|| day<1) {printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 2:sum=30;if(day>29|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 3:sum=59;if(day>31|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 4:sum=90;if(day>30|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 5:sum=120;if(day>31|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 6:sum=151;if(day>30|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 7:sum=181;if(day>31|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 8:sum=212;if(day>31|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 9:sum=243;if(day>30|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 10:sum=273;if(day>31|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 11:sum=304;if(day>30| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
case 12:sum=334;if(day>31|| day<1){printf("日期输入错误请重新输入");scanf("%d,%d,%d",&year,&month,&day);}break;
default :printf("月份输入错误，请重新输入");scanf("%d,%d,%d",&year,&month,&day);break;
}
sum=sum+day;
if(year %400 == 0 || (year%4==0&&year%100!=0))
i=0;
else
i=1;
if (i=0&&month>2)
sum++;
printf("%d",sum);
但是程序好像运行不了是为什么呢？各位大神解答下啊，还有什么更简洁的程序吗？感觉太繁琐了
