时间的几个实用函数 FILETIME UnixTime的转换

filetimeToUnixTime

windos filetime 起于 1601-01-01T00:00:00Z  ,  单位 100 纳秒

UnixTime         起于  1970-01-01T00:00:00Z  ,   单位  秒

它们的起始时间差了 11644473600 秒

下面这个函数把 filetime 转换成 UnixTime的秒偏差， 返回值 相当于 time(0),    ms 返回毫秒偏差

#define WINDOWS_TICK 10000000
#define SEC_TO_UNIX_EPOCH 11644473600LL
int64_t filetimeToUnixTime(int64_t windowsTicks, int* ms=NULL)
{
    if (ms) {
        *ms = (windowsTicks % WINDOWS_TICK) / (WINDOWS_TICK / 1000);
    }
     return (unsigned)(windowsTicks / WINDOWS_TICK - SEC_TO_UNIX_EPOCH);
}

再记录几个实用函数

1. 毫秒休眠    

// msleep(200);   休眠 200ms
void msleep(int ms)
{
#ifdef WIN32
    Sleep(ms);
#else
    usleep(ms*1000);
#endif
}

2.  获取修改文件时间

// 获取文件时间
// windows 是 创建时间(create time)    而 linux 是 改变时间 (change time)
// 调用的时候注意程序运行的 平台
bool filetime(const string& path, time_t* mtime, time_t* atime=NULL, time_t* createtime=NULL, time_t* changetime=NULL);
bool change_filetime(const string& path, time_t mtime, time_t atime);

#ifdef WIN32
SYSTEMTIME TimeToSystemTime(time_t time)
{
    tm temptm = *localtime(&time);
    SYSTEMTIME st = { 1900 + temptm.tm_year, 1 + temptm.tm_mon,
        temptm.tm_wday, temptm.tm_mday, temptm.tm_hour,
        temptm.tm_min, temptm.tm_sec, 0 };
    return st;
}
#endif

bool change_filetime(const string& path, time_t mtime, time_t atime)
{
#ifdef WIN32
    HANDLE f = CreateFileA(path.c_str(),      // LPCTSTR lpFileName,
        GENERIC_READ | GENERIC_WRITE,         // DWORD dwDesiredAccess,
        FILE_SHARE_READ | FILE_SHARE_DELETE,
        NULL,                               // LPSECURITY_ATTRIBUTES lpSecurityAttributes,
        OPEN_EXISTING,
        FILE_FLAG_BACKUP_SEMANTICS,         // DWORD dwFlagsAndAttributes,
        NULL);
    
    FILETIME fmtime, fatime;
    SYSTEMTIME local_mtime = TimeToSystemTime(mtime);
    SYSTEMTIME local_atime = TimeToSystemTime(atime);
    SYSTEMTIME sys_mtime, sys_atime;
    TzSpecificLocalTimeToSystemTime(NULL, &local_mtime, &sys_mtime);
    TzSpecificLocalTimeToSystemTime(NULL, &local_atime, &sys_atime);
    SystemTimeToFileTime(&sys_mtime, &fmtime);
    SystemTimeToFileTime(&sys_atime, &fatime);
    SetFileTime(f, NULL, &fatime, &fmtime);
    CloseHandle(f);
#else
    struct utimbuf buf;
    buf.modtime = mtime;
    buf.actime = atime;
    utime(path.c_str(), &buf);
#endif
    return true;
}

bool filetime(const string& path, time_t* mtime, time_t* atime/*=NULL*/, time_t* createtime/*=NULL*/, time_t* changetime/*=NULL*/) {
    struct stat st;
    int ret = stat(path.c_str(), &st);
    if (-1 == ret)
        return false;
    if (mtime) *mtime = st.st_mtime;
    if (atime) *atime = st.st_atime;
    
#ifdef WIN32
    if (createtime) *createtime = st.st_ctime;
    if (changetime) // windows 下没有这个时间    参数错误
        return false;
#else
    if (changetime) *changetime = st.st_ctime;
    if (createtime) // linux 下没有这个时间   参数错误
        return false;
#endif

    return true;
}

3. 时间字符串的几个转换

// time_t 转换成时间字符串
string time2date(time_t tm, const char* fmt = "%Y-%m-%d");

// yyyy-mm-dd hh:mm:ss --> time_t
// 假设你传入的时间一定是对的
time_t s2time(const string& s);

// 返回 20190528
string current_date(const char* fmt = "%d%02d%02d");
// 返回 [09:18:24.234]
string current_time();


string current_date(const char* fmt /*= "%d%02d%02d"*/)
{
	char date[40] = { 0 };

#ifdef WIN32 
	//获得当前日期
	SYSTEMTIME st;
	GetLocalTime(&st);
	sprintf_s(date, sizeof date, fmt, st.wYear, st.wMonth, st.wDay);
#else
	struct timespec now;
	clock_gettime(CLOCK_REALTIME, &now);
	struct tm *x = localtime(&(now.tv_sec));

	snprintf(date, sizeof date, fmt, 1900 + x->tm_year, x->tm_mon + 1, x->tm_mday);
#endif

	return date;
}

time_t s2time(const string& s) {
    struct tm t;
    int n = sscanf(s.c_str(), "%d-%d-%d %d:%d:%d",
                   &t.tm_year, &t.tm_mon, &t.tm_mday,
                   &t.tm_hour, &t.tm_min, &t.tm_sec);
    if (n != 6)
        return 0;

    t.tm_year -= 1900;
    t.tm_mon -= 1;
    return mktime(&t);
}

string time2date(time_t tm, const char* fmt /*= "%Y-%m-%d"*/)
{
    char ch[64] = {0};
    strftime(ch, sizeof(ch) - 1, fmt, localtime(&tm));
    return ch;
}

/* 这个函数好是好 就是不能精确到 毫秒
static string  getCurrentTimeStr()
{
	time_t t = time(NULL);
	char ch[64] = {0};
	strftime(ch, sizeof(ch) - 1, "%Y-%m-%d %H:%M:%S", localtime(&t));     //年-月-日 时-分-秒
	return ch;
}
*/

string current_time()
{
	char now[30] = { 0 };

#ifdef WIN32 
	//获得当前日期
	SYSTEMTIME st;
	GetLocalTime(&st);
	sprintf_s(now, 30, "[%02d:%02d:%02d.%03li]", st.wHour, st.wMinute, st.wSecond, st.wMilliseconds);
#else
	struct timespec ts;
	clock_gettime(CLOCK_REALTIME, &ts);
	struct tm *x = localtime(&(ts.tv_sec));

	snprintf(now, 30, "[%02d:%02d:%02d.%03li]", x->tm_hour, x->tm_min, x->tm_sec, ts.tv_nsec / (int)1E6);
#endif

	return now;
}