/**
 * 标题: Date to Date
 * 描述: 返回任意两个日期之间的天数总计 
 * 作者: hjc
 * 版本: 1.1
 * 时间: 2005.09.23
 */
//========================================
//file head
//========================================
#include <stdio.h>
//========================================
//function declare
//========================================
int DaysToElapse      (int $year, int $month, int $day);
int DaysToSurplus     (int $year, int $month, int $day);
int DaysToYearTotal   (int $year_outset, int $year_finish);
int LeapYearToCheckUp (int $year);
//========================================
//main
//========================================
int main ()
{
    int date_outset[3];
    int date_finish[3];
    
    printf("Please input outset date, for example: 2004/6/10\n");
    printf("=");
    scanf ("%d/%d/%d",
    &date_outset[0],
    &date_outset[1],
    &date_outset[2]);
    
    printf("\nPlease input finish date, form ditto...\n");
    printf("=");
    scanf ("%d/%d/%d",
    &date_finish[0],
    &date_finish[1],
    &date_finish[2]);
    
    int day_elapse  = DaysToSurplus  (
    date_outset[0],
    date_outset[1],
    date_outset[2]
    );
    
    int day_surplus = DaysToElapse (
    date_finish[0],
    date_finish[1],
    date_finish[2]
    );
    
    int total = 0;
    
    if(date_outset[0] == date_finish[0])
    {
        total =
        DaysToElapse (
        date_finish[0],
        date_finish[1],
        date_finish[2])
        -
        DaysToElapse (
        date_outset[0],
        date_outset[1],
        date_outset[2]);
    }
    else if(date_outset[0] < date_finish[0])
    {
        total = day_elapse + day_surplus;
        total += DaysToYearTotal (date_outset[0], date_finish[0]);
    }
    
    printf("\nTotal %d days between %d/%d/%d and %d/%d/%d.\n\n\n",
    total,
    date_outset[0],date_outset[1],date_outset[2],
    date_finish[0],date_finish[1],date_finish[2]);

    printf("Please any key to exit...");
    getch();
    return 0;
}    
//========================================
//function
//========================================
//检测是否为闰年 
int LeapYearToCheckUp (int $year)
{
    if($year%400==0 || ($year%4==0 && $year%100!=0))
    {
        return 1;
    }
    else
    {
        return 0;
    }
}
//计算本年逝去天数 
int DaysToElapse (int $year, int $month, int $day)
{
    int i;
    for (i=1; i<$month; i++)
    {
        if(i==2)
        {
            if(LeapYearToCheckUp ($year) == 1)
            {
                $day += 29;
            }
            else
            {
                $day += 28;
            }    
        }
        else if(i==4 || i==6 || i==9 || i==11)
        {
            $day+=30;
        }
        else
        {
            $day+=31;
        }
    }
    
    return $day;
}
//计算本年剩余天数
int DaysToSurplus (int $year, int $month, int $day)
{
    return
    DaysToElapse ($year, 12, 31)
    - DaysToElapse ($year, $month, $day);
}
//合计两年之间天数 
int DaysToYearTotal (int $year_outset, int $year_finish) 
{
    int i,$temp = 0;
    
    for (i=$year_outset+1; i<$year_finish; i++)
    {
        $temp += DaysToElapse (i, 12, 31);
    }

    return $temp;
}