how to compare two dates in datetimepicker

i am doing windows project, in which i have two datetimepicker controls, one for startdate and other for enddate


In runtime, when user selects the startdate and enddate from that controls, it should read the textfile(i.e) log.txt & search line by line get the matching of both these dates and as well as inbetween dates and write the data to a textbox or label control 


for eg in log file the some data is like below


3/12/2013 2:51:47 PM - ASDASDASD.D20131203145019 
4/12/2013 2:52:23 PM - ASDDFSDSA.C20131203145019 
5/12/2013 2:52:37 PM - SDASAFAS_20131203182101.D 
6/12/2013 3:17:11 PM - RRRTWEWA_20131203184602.D00 
7/12/2013 3:35:32 PM - XBCNXCXCXC.D0120131203153408 


if i search from 5 dec 2013 to 7 dec 2013


it should retrieve 


5/12/2013 2:52:37 PM - SDASAFAS_20131203182101.D 
6/12/2013 3:17:11 PM - RRRTWEWA_20131203184602.D00 
7/12/2013 3:35:32 PM - XBCNXCXCXC.D0120131203153408 


but uptonow i am getting


5/12/2013 2:52:37 PM - SDASAFAS_20131203182101.D 
7/12/2013 3:35:32 PM - XBCNXCXCXC.D0120131203153408 

i am retriving only the startdate & enddate matching data not inbetween date data

The below are some of the coding i have tried


string FDDate = FD.Date.ToString("M/d/yyyy");
                string TDDate = TD.Date.ToString("M/d/yyyy");


                string searchstring = EnterFileNameTextbox.Text.ToString();
                string searchfromdate = FromDateTimePicker.Value.ToShortDateString();
                string searchtodate = ToDateTimePicker.Value.ToShortDateString();
               
                string line;
                StringBuilder sb = new StringBuilder();
                int counter = 0;
                using (StreamReader file = new StreamReader(@"D:\log.txt"))
                {
                    while ((line = file.ReadLine()) != null)
                    {
                        if (line.Contains(searchstring) && line.Contains(FDDate))
                        {
                            sb.AppendLine(line.ToString());
                            counter++;
                        }                      
                       
                        else if (line.Contains(searchstring) && !line.Contains(FDDate))
                        {
                            if (FD.Date < TD.Date)
                            {                                
                                sb.AppendLine(line.ToString());
                                counter++;
                                FDDate = FD.Date.AddDays(1).ToShortDateString();
                            }
                            else if (FD.Date == TD.Date)
                            {
                                FDDate = FD.Date.ToShortDateString();
                                sb.AppendLine(line.ToString());
                                counter++;
                            }
                        }
                    }
                }  


                ResultTextBox.Text = sb.ToString();
                CountLabel.Text = counter.ToString();
            }


            catch (Exception ex)
            {
                MessageBox.Show("The file could not be read");
                MessageBox.Show(ex.Message);
            }




i am not getting idea to do the loop