两个SYSTEMTIME比较差异（秒数、天数……）的方法

原贴地址：

http://topic.youkuaiyun.com/t/20040707/08/3151675.html

 

我稍微加工了一下：

 

 

====================Begin====================

 

time_t FileTimeToTime_t(const FILETIME &ft) { ULARGE_INTEGER ui; ui.LowPart = ft.dwLowDateTime; ui.HighPart = ft.dwHighDateTime; return ((LONGLONG)(ui.QuadPart - 116444736000000000) / 10000000); } int GetDiffSeconds(const SYSTEMTIME &t1, const SYSTEMTIME &t2) { FILETIME fTime1 = { 0, 0 }; FILETIME fTime2 = { 0, 0 }; SystemTimeToFileTime(&t1, &fTime1); SystemTimeToFileTime(&t2, &fTime2); time_t tt1 = FileTimeToTime_t(fTime1); time_t tt2 = FileTimeToTime_t(fTime2); return (int)(tt2 - tt1); } int GetDiffDays(const SYSTEMTIME &t1, const SYSTEMTIME &t2) { int diffSeconds = GetDiffSeconds(t1, t2); return diffSeconds / (24 * 3600); }

====================End====================

 

 

// 我顺便补充一个：反推SYSTEMTIME隔N天之后的SYSTEMTIME

 

void Time_tToFileTime(FILETIME &ft, time_t time) { ULARGE_INTEGER ui; ui.QuadPart = (LONGLONG)(time * 10000000) + (LONGLONG)(116444736000000000); ft.dwLowDateTime = ui.LowPart; ft.dwHighDateTime = ui.HighPart; } void GetOffsetDaysTime(const SYSTEMTIME &stSrc, int offDays, SYSTEMTIME &stDst) { FILETIME fTimeSrc = { 0, 0 }; SystemTimeToFileTime(&stSrc, &fTimeSrc); time_t tmSrc = FileTimeToTime_t(fTimeSrc); time_t tmDst = tmSrc + SEC_OF_DAY * offDays; FILETIME fTimeDst = { 0, 0 }; Time_tToFileTime(fTimeDst, tmDst); FileTimeToSystemTime(&fTimeDst, &stDst); }