通过秒数计算日期与时间

#define START_YEAR (1985)
#define SECOND_DAY    (86400)    //60*60*24
#define SECOND_HOUR    (3600)    //60*60
#define SECOND_MIN    (60)    //60

const unsigned short int mon_yday[][13] =
{
/* Normal years.  */
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
/* Leap years.  */
{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};

//判断一个年份是否为闰年，是就返回1，不是就返回0
inline int isLeapYear(int year)
{
return( (year%4 == 0 && year%100 != 0) || (year%400 == 0) );
}

//获取一年的天数
inline int getDaysForYear(int year)
{
return (isLeapYear(year)?366:365);
}

//根据秒数计算日期
void getDate(int second, int& year, int& month, int& day)
{
int days = second / SECOND_DAY;
int curYear = START_YEAR;
int leftDays = days;

//calc year
int daysCurYear = getDaysForYear(curYear);
while (leftDays >= daysCurYear)
{
leftDays -= daysCurYear;
curYear++;
daysCurYear = getDaysForYear(curYear);
}
year = curYear;

//calc month and day
int isLeepYear = isLeapYear(curYear);
for (int i = 1; i < 13; i++)
{
if (leftDays < mon_yday[isLeepYear][i])
{
month = i;
day = leftDays - mon_yday[isLeepYear][i-1] + 1;
break;
}
}
}

//计算时间
void getTime(int seconds, int& hour, int& minute, int& second)
{
int leftSeconds = seconds % SECOND_DAY;
hour = leftSeconds / SECOND_HOUR;
minute = (leftSeconds % SECOND_HOUR) / SECOND_MIN;
second = leftSeconds % SECOND_MIN;
}