从日期列表中查找日期

Question

在数据表中捕获日期。 例如，如果日期列包含 20 个日期值，则 19 个日期值相同，只有一个日期不同。 我怎样才能捕捉到不同的日期？

var directories = Directory.GetDirectories(directory);

foreach (string subdirectory in directories)
{
    // Getting the values of count file
    DateTime Count_L_M_D;
    string Count_File_Name;
    string[] Count_filePath1 = Directory.GetFiles(subdirectory, "*.count");
    string Content = File.ReadAllText(@Count_filePath1[0]);
    string loadedDate = DateTime.ParseExact(Content.Substring(9, 8), "yyyyMMdd",
                    CultureInfo.InvariantCulture).ToString("yyyy/MM/dd");
    DateTime Datevalue = DateTime.Parse(loadedDate);
    Count_File_Name = Path.GetFileName(Count_filePath1[0]);
    Count_L_M_D = Directory.GetLastWriteTime(Count_filePath1[0]);
    row["Count_File_Date"] = Datevalue;
    row["Count_File_Name"] = Count_File_Name;
    row["Count_File_LMD"] = Count_L_M_D;
    row["File_Path"] = subdirectory;
    // added the datevalue in a list
  List<DateTime> CountFileDate = new List<DateTime>();
  CountFileDate = Datevalue;
}