变量返回空值

Question

我正在编写一些代码，这些代码将搜索txt文件并将其转换为其他格式。当我尝试从文本值中获取日期时，当我知道我的正则表达式工作正常时，它将返回null。

我曾尝试制作if语句来检查match.success。香港专业教育学院成功地将日期抓到一个列表中，但其他所有值都为null，这无济于事。

    var ofd = new OpenFileDialog
        {
            Filter = "TRC File (*.trc*)|*.trc*",
            Multiselect = true,
        };

        ofd.ShowDialog();

        string path = ofd.FileName;
        List<string> alllinesText = File.ReadAllLines(path).ToList();
        string pattern = @"([0-9]{1,6}.\d).............\w(\w\w\w)\s\s...(\w\w.\w\w.\w\w.\w\w.\w\w.\w\w.\w\w.\w\w)";
        string datepattern = @"[0-9]{1,2}.\d\d.\d\d\d\d\s\d\d.\d\d.\d\d.\d\d\d";
        RegexOptions options = RegexOptions.Multiline;
        List<string> all = new List<string>();
        string info = File.ReadLines(path).ToString();

        var date = Regex.Match(info, datepattern, options);
        string datetime = Convert.ToString(date);
        DateTime mydate = DateTime.ParseExact(datetime, "MM/dd/yyyy HH:mm:ss.fff", System.Globalization.CultureInfo.InvariantCulture);



        foreach (string line in alllinesText)
        {

            foreach (Match m in Regex.Matches(line, pattern, options))
            {
                string timems = m.Groups[1].Value;
                TimeSpan ms = TimeSpan.Parse(timems);
                DateTime combined = mydate.Add(ms);
                string finaltime = combined.ToString();
                string matchid = m.Groups[2].Value;
                string matchdata = m.Groups[3].Value;
                matchdata = Regex.Replace(matchdata, @"\s+", "");
                string iddata = finaltime + "," + matchid + "," + matchdata;
                all.Add(iddata);
            }
        }

        TextWriter tw = new StreamWriter(@"C:\Users\Public\test.txt");

        foreach (string s in all)
        {
            tw.WriteLine(s);
        }
        tw.Close();
    }

我正在尝试在文本文件的标题中获取开始日期。

    ;$FILEVERSION=1.1
    ;$STARTTIME=43626.4234913889
    ;
    ;   C:\Users\acarducci\Desktop\chris trace.trc
    ;
    ;   Start time: 6/10/2019 10:09:49.656.0
    ;   Generated by PCAN-View v4.2.1.533
    ;
    ;   Message Number
    ;   |         Time Offset (ms)
    ;   |         |        Type
    ;   |         |        |        ID (hex)
    ;   |         |        |        |     Data Length
    ;   |         |        |        |     |   Data Bytes (hex) ...
    ;   |         |        |        |     |   |
    ;---+--   ----+----  --+--  ----+---  +  -+ -- -- -- -- -- -- --
         1)         2.0  Rx         0400  8  01 5A 01 57 01 D2 A6 02 
         2)         8.6  Rx         0500  8  02 C1 02 C9 02 BE 02 C2 
         3)        36.2  Rx         0401  8  01 58 01 59 01 01 01 01