c++通过时间戳获得自定格式时间

//通过时间戳得到字符串日期（年月日）

std::string VHelper::GetTimeStringByTimeStamp( time_t timeStamp )
{
    timeStamp += 28800;
    struct tm *pt;
    pt = gmtime( &timeStamp );
    char str[100];
    strftime( str, sizeof( str ), "%Y-%m-%d", pt );

    std::string timeStr( str );

    return timeStr;
}

//通过时间戳得到字符串日期(年月日时分秒格式)

std::string VHelper::GetYMDHMSTimeStringByTimeStamp( time_t timeStamp )
{
    timeStamp += 28800;
    struct tm *pt;
    pt = gmtime( &timeStamp );
    char str[100];
    strftime( str, sizeof( str ), "%Y-%m-%d %H:%M:%S", pt );

    std::string timeStr( str );

    return timeStr;
}

通过时间戳得到字符串的时间（时分秒）

std::string VHelper::GetHMSTimeStringByTimeStamp(time_t timeStamp)
{
    timeStamp += 28800;
    struct tm *pt;
    pt = gmtime( &timeStamp );
    char str[100];
    strftime( str, sizeof( str ), "%H:%M:%S", pt );

    std::string timeStr( str );

    return timeStr;
}