Windows获取时间函数（使用GetLocalTime，GetSystemTime，SystemTimeToTzSpecificLocalTime，GetFileTime API函数

获取本地时间

typedef struct _SYSTEMTIME {
  WORD wYear;
  WORD wMonth;
  WORD wDayOfWeek;
  WORD wDay;
  WORD wHour;
  WORD wMinute;
  WORD wSecond;
  WORD wMilliseconds;
} SYSTEMTIME,
  *PSYSTEMTIME;

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11

1.GetLocalTime获取的是本地时区时间

SYSTEMTIME localSysTime;
GetLocalTime(&localSysTime);

• 1
• 2

2.GetSystemTime获取的是UTC时间

SYSTEMTIME utcSysTime;
GetSystemTime(&utcSysTime);

• 1
• 2

Note: 
UTC(Universal Time Coordinated),协调世界时,又称世界标准时间或世界协调时间. 
UTC与格林尼治平均时一样,都与英国伦敦的本地时相同. 
整个地球分为二十四个时区,每个时区都有自己的本地时间. 
北京时区是东八区,领先UTC八个小时.(UTC+8) 
伦敦时间为UTC+0. 
也就是说,若全球标准时间是2012-07-04 00:00:00,则北京时间为2012-07-04 08:00:00.

3.UTC时间和具体时区时间的转换

<1> UTC Time –> Local Time

BOOL WINAPI SystemTimeToTzSpecificLocalTime(
  __in          LPTIME_ZONE_INFORMATION lpTimeZone,
  __in          LPSYSTEMTIME lpUniversalTime,
  __out         LPSYSTEMTIME lpLocalTime
);

• 1
• 2
• 3
• 4
• 5

lpTimeZone 
A pointer to a TIME_ZONE_INFORMATION structure that specifies the time zone of interest. 
If lpTimeZone is NULL, the function uses the currently active time zone. 
所以将lpTimeZone设为NULL就会将UTC时间转换为本地时间

<2> Local Time –> UTC Time

BOOL WINAPI TzSpecificLocalTimeToSystemTime(
  __in          LPTIME_ZONE_INFORMATION lpTimeZoneInformation,
  __in          LPSYSTEMTIME lpLocalTime,
  __out         LPSYSTEMTIME lpUniversalTime
);

• 1
• 2
• 3
• 4
• 5

类同.

File Time

我们在Windows系统中获取文件的创建时间,存取时间,修改时间可以使用下面的API.

BOOL WINAPI GetFileTime(
  __in          HANDLE hFile,
  __out         LPFILETIME lpCreationTime,
  __out         LPFILETIME lpLastAccessTime,
  __out         LPFILETIME lpLastWriteTime
);

• 1
• 2
• 3
• 4
• 5
• 6

获取的时间为UTC FILETIME.

typedef struct _FILETIME {
  DWORD dwLowDateTime;
  DWORD dwHighDateTime;
} FILETIME, *PFILETIME;

• 1
• 2
• 3
• 4

Contains a 64-bit value representing the number of 100-nanosecond intervals since January 1, 1601. 
表示从时间1601-06-01起的100纳秒间隔数.

对于时间的显示,使用SYSTEMTIME为好. 
而对于时间的计算&比较,使用FILETIME为好.

Note:使用GetFileTime获取的FILETIME为UTC FILETIME.

FILETIME比较函数:

LONG WINAPI CompareFileTime(
  __in          const FILETIME* lpFileTime1,
  __in          const FILETIME* lpFileTime2
);

• 1
• 2
• 3
• 4

-1— First file time is earlier than second file time. 
0 —- First file time is equal to second file time. 
1 —- First file time is later than second file time.

FILETIME <–> SYSTEMTIME

FileTimeToSystemTime 
SystemTimeToFileTime 
FileTimeToLocalFileTime 
LocalFileTimeToFileTime

对于利用GetFileTime获取的UTC FILETIME怎样转换为Local SYSTEMTIME 
GetFileTime–>UTC FILETIME–>(FileTimeToSystemTime)–>UTC SYSTEMTIME–>(SystemTimeToTzSpecificLocalTime)–>Local SYSTEMTIME 
GetFileTime–>UTC FILETIME–>(FileTimeToLocalFileTime)–>Local FILETIME–>(FileTimeToSystemTime)–>Local SYSTEMTIME

时间间隔的运算

将FILETIME–>LARGE_INTEGER,再通过LARGE_INTEGER进行运算

typedef union _LARGE_INTEGER {
  struct {
    DWORD LowPart;
    LONG HighPart;
  };
  struct {
    DWORD LowPart;
    LONG HighPart;
  } u;
  LONGLONG QuadPart;
} LARGE_INTEGER,  *PLARGE_INTEGER;

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11

eg:

FILETIME time1;
FILETIME time2;
LARGE_INTEGER liTime1;
LARGE_INTEGER liTime2;
liTime1.LowPart = time1.dwLowDateTime;
liTime1.HighPart = time1.dwHighDateTime;
liTime2.LowPart = time2.dwLowDateTime;
liTime2.HighPart = time2.dwHighDateTime;
LARGE_INTEGER liElapsedTime;
liElapsedTime.QuadPart = liTime2.QuadPart - liTime1.QuadPart;
liElapsedTime.QuadPart /= 10000000;  //相差的秒数

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11

时间的转换公式: 
1微秒 = 1000 纳秒 
1毫秒 = 1000 微秒 
1秒 = 1000毫秒

http://blog.csdn.net/hisinwang/article/details/45116133