StreamReader

StreamReader

• AlexJD

  M Nicholas,

  I think SJ had a point. I believe he was suggesting a way to simplify..

  in a real way, the endmarker doesn't signify anything the the begin marker or EOF wouldn't signify.

  
  
  

• _Othello_

  You can do it that way and read the entire file in and then try processing it using string / array functionality but again you still have to determine the start and stop points.

  I only continued using the streamreader as this is what you'd done at the initial code sample and title of the thread but if you are reading the entire contents in and then processing them in memory you can load the entire contents of the file into a string using a single line.

  dim s as string = My.Computer.FileSystem.ReadAllText (<FileName>)

  which will read the entire contents of the file into the string variable s. Then you could split the string as your doing and write a algorithm to loop through the array elements. It would be pretty similar to the Streamreader looping process but use the array.

  There are possible advantages / disadvantages

  1. You load the entire file into memory (which could be ok for a small amount of items but with a huge amount of items this could suck up memory)

  2. Accessing memory is potential quicker than accessing disk. (How frequently are you doing this action as if its occuring like 100's or 1000's of times then disk access you may notice the difference between file and memory access)

  3. Is this file contents or array changing frequently during the running of the application and do they need to be kept in sync. Are you modifying the item and then want it reflected immediately afterwards.

  All issues to consider....

  
  

• Dae Yeon Jo

  It works

  My only comment on it is you are physically adding every single item line in the families preceeding the actually family you want to load and then clearing these when you find the family you really want to populate.

  Populating listboxes it reletively slow for large amounts of items. Even though you are physically only wanting say 4 people loaded - if we are family 1000 we may have populate 6000 (4 people + End String + Start Strings) only to remove all of these items to populate 4 items.

  So you may find that the performance seriously drops of for large numbers of families.

  
  

• AJOY KUMAR

  Spotty~

  Without boring you with a lengthy explanation of the program I am constructing (hence the simplistic “family” example), the software is for my wife’s business. I anticipate having 4 or 5 categories, the largest of which will have 20 items (the smallest, maybe 3).

  The crux of the issue though, is that one of the categories will be employees (of which there is a normal amount of turnover). So my plan is to have any part of the software that deals with a list that may be in flux, to fill it’s variables via an easy to amend text file. This way, my (less than computer savvy) wife can easily update the software variables herself.

  Thanks again for helping me (twice now) with this venture into writing my own software. I truly appreciate it.

  Mike

  
  

• DDressel

  I took your concerns to heart and added something similar to what you were doing in your original code.

  ----------------------------

  Dim objFS As New FileStream("C:\test\test.txt", FileMode.Open, FileAccess.Read)

  Dim objSR As New StreamReader(objFS)

  Dim TextSays As String

  Dim StartString As String = "[Start family:B]" 'category start marker

  Dim EndString As String = "[End family:B]" 'category end marker

  Dim blnFound As Boolean 'True or False that category start was reached

  Do While Not objSR.EndOfStream

  TextSays = objSR.ReadLine

  If TextSays = StartString Then 'loops through list until category start maker if found

  blnFound = True

  If blnFound = True Then 'if marker is found...

  Exit Do 'exit the loop

  End If

  End If

  Loop

  Do While Not objSR.EndOfStream

  TextSays = objSR.ReadLine 'reads first line after previous loop (StringStart)

  ListBox1.Items.Add(TextSays) 'adds to ListBox1

  If TextSays = StartString Then 'category start marker

  ListBox1.Items.Remove(TextSays) 'clears category start maker from list

  ElseIf TextSays = EndString Then 'finds end of category marker

  ListBox1.Items.Remove(TextSays) 'removes end marker from list

  Exit Do 'exits do loop before entering another category

  End If

  Loop

  objFS.Close()

  ------------------------

  I think this is the ticket!

  
  

• developer74

  The performance probably wont be a great issue for the numbers you are talking about - but I just commented on this as others may see this use it as an example and complain when they try and populate 1000 groupings and find it is pretty slow.

  
  

• Krystan Honour

  Hey Spotty~

  (Still goofing around with possibilities)

  What do you think about this

  (test.txt File)

  [Start family:A]
  Mike
  Jim
  Tom
  Jean
  [End family:A]

  [Start family:B]
  Steve
  Dave
  Ted
  Bob
  [End family:B]

  ---------------------------------

  Dim objFS As FileStream

  Dim objSR As StreamReader

  Dim TextSays As String

  objFS = New FileStream("C:\test\test.txt", FileMode.Open, FileAccess.Read)

  objSR = New StreamReader(objFS)

  Dim StartString As String = "[Start family:B]"

  Dim EndString As String = "[End family:B]"

  Do While Not objSR.EndOfStream

  TextSays = objSR.ReadLine

  ListBox1.Items.Add(TextSays)

  If TextSays = StartString Then

  ListBox1.Items.Clear()

  ElseIf TextSays = EndString Then

  ListBox1.Items.Remove(TextSays)

  Exit Do

  End If

  Loop

  ------------------------

  This particular sub would be attached to a button addressed to the category Family "B". For each particular category, another button with a similar sub.

  It seems simple and clean to me, but do you see any issues

  As always, I value your input.

  
  

• Jero

  SJ~

  The idea is that I am writing a program with several parameters (employees, supervisors, clients, cost ratios, etc). Each of these parameters are susceptible to change. Rather than filling a ListBox with each employee’s name, thereby making it “hard coded” into the program, I want the program to fill all of it’s variables, listboxes, and the like, from a text file that any user could easily change or add to.

  So, I have made one text file that has each category, and everything that belongs to that category, listed top to bottom. The reason for start markers and end markers (on each category) is so that the program knows where to look for that information.

  [Start family:A]
  Mike
  Jim
  Tom
  Jean
  [End family:A]

  [Start family:B]
  Steve
  Dave
  Ted
  Bob
  [End family:B]

  Does that make sense Or, does it answer your question Were you thinking of another way

  Mike

  
  

• Nurax

  Hi Spotty…Thanks for responding.

  You’re suggestion looks good, I’m going to give it a try.

  What I have been goofing around with (unsuccessfully) is to split the ReadToEnd result into a string Array and try to loop through it until I find the two desired (starting and stopping) points. Somehow decipher which index numbers from an (unknown sized) array these two points are and have each index number’s string equivalent populate a list box.

  I made my array:

  --------------

  Dim strStringArray() As String = TextBox1.Text.Split()

  ---------

  (TextBox1.Text being the result of the ReadToEnd command given to the StreamReader.)

  I can now have a msgbox display any of the string members of the array, but to be effective, I need to figure out (in a looping statement) which index numbers the two desired points are ([start:A],[end:A])

  Other than the fact that I can’t figure out how to write the proper code to fit my design idea, do you think it has any merit

  Appreciate your input
  

• Tonychen

  So the following code will work with a file format like the following

  [Start family:A]
  Tom
  Mike
  Jim
  Jean
  [End family:A]

  [Start family:B]
  Bob
  Dave
  Ted
  Steve
  [End family:B]
  

  Imports System.IO

  Class Form1
  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
  Dim objFS As FileStream
  Dim objSR As StreamReader
  Dim TextSays As String

  
  Dim StrFamily As String = Me.TxtFamily.Text
  If StrFamily.Length > 0 Then
  Dim StartString As String = "[Start family:" & StrFamily & "]"
  Dim EndString As String = "[End family:" & StrFamily & "]"
  Dim blnInFamily As Boolean = False

  Me.ListBox1.Items.Clear()

  Try
  objFS = New FileStream("C:\test1.txt", FileMode.Open, FileAccess.Read)
  objSR = New StreamReader(objFS)

  Do While Not objSR.EndOfStream
  TextSays = objSR.ReadLine
  If TextSays = StartString Then '//Found Start Tag
  blnInFamily = True
  ElseIf TextSays = EndString Then '//Found End Tag
  blnInFamily = False
  Else
  If blnInFamily = True Then '//In Tag Boundaries so add each line to the listbox items
  Me.ListBox1.Items.Add(TextSays)
  End If
  End If
  Loop
  objFS.Close()
  Catch ex As Exception
  MsgBox(ex.Message)
  End Try
  End If

  End Sub
  End Class
  

  It will pick up the family name from the textbox and populate a listbox with all the lines of peoples names in that tag.

  I'm sure there are even easier ways if you want to go down the XML route and change the file format to XML but this way is a simple parser for a simple ASCII file, which was what you were asking.

  
  

• ACSM99

   

   

  Ohhhh, I see what you're talking about...Not 'why are there markers',  but do you need one on both ends.

  Interesting...Of course, your both right programatically, I'll just have to think about whether it has an effect on my "user friendly" design of the txt file. Thanks for clarifying that, ReneeC.

   

  Mike

  
  

• Peter L

  Just throwing a thought out there, why not completely remove the end marker why do you need it

  
  
  

• Mark Hopkins - MSFT

  Spotty~

  Thanks for the further thought...

  I'll have to ponder the issues and pick a route. Thanks again.

  Mike

  
  
• StreamReader