/*************************************************************************
该程序功能:
          1.输入年、月、日判断这天是星期几
          2.打印出其中的闰年
          3.计算从1600到输入时间，总共的天数
说明:
     输入的年份必须大于1600
**************************************************************************/

#include <stdio.h>

/* 计算某一天是这年中的第几天 */
int calculate_days(int year,int month,int day)
{
   
 int cnt;
    int leapYear = 0;

    if((month > 12 || month < 0) || (day > 31 || day < 0))
    {
        printf("input month or day error,please input correct data\n");
        return -1;
    }

    /* 判断是否为闰年 */
    if((year%4==0&&year%100!=0)||year%400==0)
    {
        leapYear = 1;
    }
   
 switch(month)
 {
       
  case 1:           
    cnt = day;
    break;
  case 2:
    cnt = 31 + day;
        break;
  case 3:
             if(leapYear)
             {
                 cnt = 31 + 29 + day;
             }
             else
             {
                 cnt = 31 + 28 + day;
             }
             break;
  case 4:
             cnt = 31 + 28 + 31 + day;
             break;
  case 5:
             cnt = 31 + 28 + 31 + 30 + day;
             break;
  case 6:
             cnt = 31 + 28 + 31 + 30 + 31 + day;
             break; 
  case 7:
             cnt = 31 + 28 + 31 + 30 + 31 + 30 + day;
             break;
  case 8:
             cnt = 31 + 28 + 31 + 30 + 31 + 30 + 31 + day;
             break;
  case 9:
             cnt = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + day;
             break;
  case 10:
             cnt = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + day;
             break; 
  case 11:
             cnt = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + day;
             break;
  case 12:
             cnt = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30 + day;
             break;
        default :
             printf("input month error!!\n");
             break;
            
 }
    printf("The day is %dth days for this year\n",cnt);
 return cnt;
}

/* 计算从1600年1月1日到输入的日期总共的天数 */
int total_day(int year,int month,int day)
{
    int i = 0;
    int sumDays = 0;

    if(year<1600)
    {
        printf("Does not support the query is less than 1600 years\n");
        printf("please input more than 1600 years\n");
        return -1;

    }
    for(i=1600;i<year;i++)
    {
        if((i%4==0&&i%100!=0)||i%400==0)
        {
            sumDays += 366;
            printf("leapyear=%d\n",i);
        }
        else
        {
            sumDays += 365;
        }
    }
   
    sumDays += calculate_days(year,month,day);
    printf("sumDays=%d\n",sumDays);
    return sumDays;
}

int main(int argc,char *argv[])
{
    int totalDays = 0;
    int remind = 0;
    int result = 0;
    int year = 0;
    int month = 0;
    int day = 0;
   
    printf("please year-month-day data\n");
 scanf("%d-%d-%d",&year,&month,&day);

    totalDays = total_day(year,month,day);
    if(totalDays<0)
    {
        printf("total_day error!\n");
        return -1;
    }
   
    remind = totalDays % 7;
    result = ((remind - 1) + 6)% 7;
    switch(result)
    {
        case 0:
            printf("This day is Sunday\n");
            break;
        case 1:
            printf("This day is Monday\n");           
            break;
        case 2:
            printf("This day is Tuesday\n");           
            break;
        case 3:
            printf("This day is Wednesday\n");           
            break;
        case 4:
            printf("This day is Thursday\n");           
            break;
        case 5:
            printf("This day is Friday\n");           
            break;
        case 6:
            printf("This day is Saturday\n");           
            break;
        default:
            break;
    }
    return 0;
}

输入年、月、日计算是星期几