C#把时间秒数转化成时间格式字符串00:00:00

    string TransTimeSecondIntToString(long second)
    {
        string str = "";
        long hour = second / 3600;
        long min = second % 3600 / 60;
        long sec = second % 60;
        if (hour < 10)
        {
            str += "0" + hour.ToString();
        }
        else
        {
            str += hour.ToString();
        }
        str += ":";
        if (min < 10)
        {
            str += "0" + min.ToString();
        }
        else
        {
            str += min.ToString();
        }
        str += ":";
        if (sec < 10)
        {
            str += "0" + sec.ToString();
        }
        else
        {
            str += sec.ToString();
        }
        return str;
    }