C++时间操作的汇总

1. 获取当前时间
 time_t cur_time = time(NULL);
 
2. 把整数时间转为字符串时间
string GetStringTime(const time_t time)
{
    struct tm    *lptmNow;
    char        sTime[sizeof("2010-12-21 12:39:56")];

#ifdef _WIN32
    lptmNow = localtime(&time);
#else
    struct tm    tmNow;
    lptmNow = localtime_r(&time, &tmNow);
#endif
    
    // 获得对应时间的日期
    char szBuf[32];
    snprintf(szBuf, sizeof(szBuf), "%04d年%02d月%02d日",
             lptmNow->tm_year + 1900,
             lptmNow->tm_mon + 1,
             lptmNow->tm_mday);
             
    int week = lptmNow->tm_wday;    //获得星期几
    int hour = lptmNow->tm_hour;    //获得小时
    int min = lptmNow->tm_min;    //获得分钟
    int sec = lptmNow->tm_sec;    //获得秒

    // 返回字符串时间
    memset(sTime, 0, sizeof(sTime));
    size_t length = strftime(sTime, sizeof(sTime), "%F %T", lptmNow);
    return string(sTime, length);
}

3. 获得当前毫秒
unsigned long long GetCurMillSecond()
{
    unsigned long long dwPreciseTime;
#ifdef _WIN32
    struct _timeb    tbNow;
    _ftime(&tbNow);
    dwPreciseTime = (unsigned long long)tbNow.millitm;
#else
    struct timeval    tvNow;
    gettimeofday(&tvNow, NULL);
    dwPreciseTime = (unsigned long long)(tvNow.tv_sec*1000 + tvNow.tv_usec/1000);
#endif
    return dwPreciseTime;
}

4. 随机数种子初始化
void InitRand()
{
    int    Second;
    int USecond;
#ifdef _WIN32
    struct _timeb    tbNow;
    _ftime(&tbNow);
    Second = (int)tbNow.time;
    USecond = tbNow.millitm;
#else
    struct timeval    tvNow;
    gettimeofday(&tvNow, NULL);
    Second = tvNow.tv_sec;
    USecond = tvNow.tv_usec;
#endif

    srand(Second * USecond);
}

5. 线程睡眠，单位为微妙
void USleep(unsigned long USeconds)
{
#ifdef _WIN32
    Sleep(USeconds / 1000);
#else
    struct timeval oDelay;
    oDelay.tv_sec = (unsigned long)USeconds / 1000000;
    oDelay.tv_usec = (unsigned long)USeconds % 1000000;
    select(0, 0, 0, 0, &oDelay);
#endif
}

6. 解析日期时间为整数时间
time_t ParseDateTime(const char* str)
{
    struct tm tm = {};

#ifdef _XOPEN_SOURCE
    const char* end = strptime(str, "%F %T", &tm);
    if (end && end - str >= int(sizeof("2013-02-14 00:00:00") - 1))
        return mktime(&tm);
#else
    if (sscanf(str,
               "%u-%u-%u %u:%u:%u",
               &tm.tm_year, &tm.tm_mon, &tm.tm_mday,
               &tm.tm_hour, &tm.tm_min, &tm.tm_sec
              ) == 6)
    {
        tm.tm_year -= 1900;
        tm.tm_mon -= 1;
        return mktime(&tm);
    }
#endif

    return time_t(-1);
}