Save Data To Random Access Files?

Sep 6, 2010

how do you save data stored in an array of records (structure) to a text file using StreamWriter? I currently have

Private Sub btnSaveToFile_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSaveToFile.Click
Dim sw As New StreamWriter(New FileStream("EmployeeDetails.txt", FileMode.Create, FileAccess.Write))
For Each record As EmployeeType In employees


but it doesn't work. My array is fixed and currently has 3 elements (for testing purposes). If I enter two records and add these to the structure I get the following data saved to the text file:


How do I stop unused elements of the array being included when writing to file? Should I use a dynamic array instead and if yes, how do you use dynamic arrays with structures?


Converting VB5 To VB2010 - Random Access Files?

Jul 27, 2011

I am trying to convert a VB5 program to VB2010 so that I can continue to support it on my new PC. My copy of VB5 was an upgrade from VB3 which was an upgrade from VB2 which came on floppies, so I can't just install every preceding version as my new PC doesn't have a floppy drive.I have accepted that I will have to design all the forms from scratch (whatever happened to twips?) and will have to go through the thousands of lines of code line-by-line, but I have hit a brick wall when it comes to random access files. One such file is defined in the Declarations section of Module1 thus:[code]....

I soon found I had to change Type to Structure, but then in the declaration of transrec, transtype acquired a wavy blue underline with the error message: "'transrec' cannot expose type 'transtype' in namespace 'Treasurer_2010' through module 'Module1'.So if I can't use the structure in the module in which it is declared, where can I use it?

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Nov 2, 2009

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Now for a bit of background the file is made up of 27 fixed length records of 256 bytes. Each of the records has a separate structure consisting of 30-120 fields. The proplem I am having is I can create the record structures but when using the FileGet method I am receiving an error. Now I have found samples that showed the same format I am using that claim to work.

The error I am getting is Option Strict On disallows narrowing from type 'System.ValueType' to type 'ProgramName.ModuleName.Record' in copying the value of 'ByRef' paramater 'Value' back to the matching argument.

The basic layout (simplified) is as follows:

Structure Record
<VBFixedString(6)> Public SomeParam as String
Public SomeNumber as Short


Now the overloads for FileGet show all of the data types including Object. But I have tried various methods to retreive the 256 byte record but without success. Do I have to actually read each of the several hundred fields of the structure one by one? Or am i overlooking something (I have been known for this in the past)

Or (and I'll kick myself if this is the only way) do I just have to set option strict Off in the module and the code as above will actually work.

I would love to be able to just ditch the random access file but I have to keep it for compatibility with several other applications at this time.

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Oct 30, 2010

I have 15 years' worth of files (approx. 10,000) that were created using VB6 structures and stored using the random access method. I am trying to write a conversion routine that will read the old structures and put them into a new format that is more compatible with the .net environment. I have not been able to successfully read any of the old files using the tools available in .net. Each file starts with a header record structure. The header record tells me how many tags are in the file. The next record (ie record number 2) is the first tag pointer record in the file. 

There are num_of_tags of the pointer records. Each pointer record has the string that holds the tag's 'literal name and two long integers that tell where in the file this tags records are. Those actual records are stored as History data structures, [Code]

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Feb 24, 2010

This time, basically, i'm working with Random Access Files.I have this et of code to read data from a form a save it into a .dat file. This works fine.

Public Class frmDramaClub
Structure MemberRecord
Dim ID As Integer[code].....

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Jan 16, 2012

I'm trying to convert an old Quick BASIC program to VB.Net. There doesn't appear to be any direct replacement for the old file statements. Building a database seems like overkill for my simple needs.

How can I do the following in VB.Net?

OPEN "test.dat" FOR RANDOM AS #1 LEN = 20
FIELD #1, 10 AS a$, 10 AS b$
LSET a$ = "One"
LSET b$ = "Two"
PUT #1, 1
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Jan 24, 2009

I'm working with random access files. I created a module and in it put the

Structure PersonData
Dim Name as String
Dim Age as Integer[code]....

The problem is strange... it will let me input string lengths of 3 for Person.Name and Person.Description and it will save correctly, however, the moment I try and lengthen the string (or even if it's longer than 3 to begin with), I get a 'bad record number' error.

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I have recently decided to give .net another chance, but i have a few questions about it before i get really into it. RE: Files, I use random access files to store data as opposed to databases (namely i don't see the need for a database for storing so little information(records <200 max) knowing that it is an older system and less "cool" i don't care...) Will vs2010 express read, write to random access files? Would it be done kind of like vb6 (which is my current vb version)? I will be needing to print the text of rich text boxes, is vs2010 express capable of doing this?

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Mar 22, 2011

im used to C programming.

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The problem is that if I save a file I get "myfile.GDL" if I overwrite that I get a new file "myfile.GDL.GDL" ect.the other problem being that the filtering in the windows save/open dialog wont show .GDL files unless I select "all files".

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May 2, 2009

I am trying to save multiple text files using a save dialog.

I can save one textbox

Dim File As System.IO.File
Dim Write As System.IO.StreamWriter
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but I don't know how to save multiple textboxes and richtext boxes. Would I have to use a screenwriter for this?

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I am writing the source code to write the random files name but I don't know how to write that in Here it is the


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I am making a basic form that has 1 button and a rich text box.I need to click on the button and have it call a random line from 3 text documents (so 3 lines total) and place them in the rich text box, each on a different line.

"Quick example"

3 Text files

Click on button named generate and in the text box below it places

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I have this at the moment:

Sub Import()
Dim db As Database
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Ok I know this question has been asked to death but I still have not seen a good answer. I have created an application in VS2010 using VB.NET. In my application I have an error log that is an XML file located in the Public gstLocalErrorLogLocation As String = Application.StartupPath & "ErrorLog"that gets written to in the event of an error so I can trouble shoot application easier. My application also downloads files from our FTP site and puts the files in Public gstLocalDownloadLocation As String = Application.StartupPath & "download"So I have files that get read and written to as well and created and deleted all in the Application.StartupPath which is either "c:Program Files(Application Directory)(Some Directory)(Some File)" or "c:Program Files (x86)(Application Directory)(Some Directory)(Some File)" depending on 32bit or 64bit Windows 7.

After creating the setup I install it on my test machine that have both Windows 7 32bit and 64bit.Everything in the application works great till I have to write to, delete or creat a file in those directories above. I know it is an access issue and the UAC. This will get installed on numerous systems so the options I have seen to change file or folder permission on the computers manually is not an option.What has to happen is after I install the application it just works like when you install it on XP. Some post have suggested that you us a user with administrator privilages or group which is all fine and dandy but the user I have used to test the application has all of that.

So what I am asking is how do you create an application with VS2010 in VB.NET that after creating a setup package and installing on Windows 7 will just work with out "Access to the path c:Program Files(Application Directory)(Some Directory)(Some File) is denied." If I have to install this on 100 Windows 7 computers it has to be a concreate no manually doing anything just install and work like when we installed on XP.

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May 2, 2009

i have to write a simple Hangman game with sum extra features for bonus points.... the funny thing is i can write the code for the extra features such as "adding additional word, help menu...etc",but i cant write the main program,The program must select random word from text files, it have three difficulities, the codes should be the same for all three, just read from different files...(well thats what i think)... i think i hav to use array... but how do i read the contain of the text file into an array n randomly select a word?


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May 23, 2010

I wanta make a autoupdater with my website but the thing is that the files i upload always have a random link it not like [URL] its like [URL]. so can i still get the autoupdate i saw some tuts with it i got it to read the txt but i was thnk that can i make it read a txt with the link in it then goes to it

Here is what i want it to do

Start Program>Click Update>ReadtxtVerison(website)>ReadLinkLocation(website)>Goes to link in the link.txt>Downloads>Deletes Old Ver>restarts
thats would be awesome if u get it for me and thz

This is wut i got so far

Private Sub Start_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub


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Jul 1, 2010

I need an example of how to create and use a random access file

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Created Structure
opened file using FileOpen(1, "filename.dat", OpenMode.Random, , , bytes in structure)
used structure .ID = record number
FilePut(1, structure)
The program enters the first record but although when I enter more records it still shows only one record in the file.

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Jan 15, 2010

I am moving all of the prgrams that I have written, to VS2008. However, I use Random Access File Foemat for the databases that have been used for over a decade. I need to be able to read and write to a Random access file.I have multiple fields in the database and cannot lose access to this information.VS2008 doesn't use the following type of code to define the Fields that will be used in the Database. I did what it suggested, using the Structure / End Structure, but that was as close to a solution that I could find in the Help Files.

Type EquipType
    EquipName As String * 32
    Location As String * 28[code].......

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Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
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Apr 25, 2010

I'm doing a Program for a Friend of mine, He Want to have a Console Program Running on his Computer.OK the problem i am having is With Stream Read, I have 3 test users inside Test File, if User 1 logs in his information is store in logged file with time and data.but if User 3 logs on user 1 2 and 3 are all saved on the logged file

i dont have read to end of file in my Code.i dont have my Program with me, so i going off the top of my head i have something like this what i want to be able to find out how to do is Right from any part of the file and out put it, I take it i need to use Random Access but how to i code Random Access for this type of file. All i can find is how to Randomly place Words in a text file with Length and size.


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I achieved reading and writing data to a random access file, buthow do I write and read data from a certain position in the *.txtfile? Would it be better if I created multiple file modes to

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Jan 30, 2010

I am using Visual Basic 2009 to create a file of records to store students tests scores.Currently i can write to the file, create new records etc. However i cannot edit a particular record, im sure i have to use file seek function but i have no idea where to is some of my source code to give you an idea of where im at

Do While (Not EOF(1)) And found = False 'loop until no more records or the record is found
nosrecords = nosrecords + 1
FileGet(1, onestudent, nosrecords)[code].....

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Sep 3, 2010

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Nov 17, 2010

I'm tasked with the job of creating a javascript version of a units conversion application written in vb6. I have the source code but I don't have vb 6. The source code uses a dat file to hold a conversion array (unit type, unit, xfactor, plusfactor). Getting the data out of this file would be good to me. I tried creating a little app in vb 2010 to write the data from that dat file to a txt file using essentially the same code as the source code. And that has been somewhat successful (took a while to figure out the fixed string business). Now I can pull the data out as an array. The math elements of this array look fine but the strings are somewhat read-able but too garbled to use. I can't seem to fix that by changing the character set/encoding.

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Jun 22, 2010

I am trying to generate random images from access database using hashset as it is said to be unique and there won't be any repeated images appearing. But, it doesn't seem to work.

How can i get it to work? By the way, i am very new to the concept of hashset.
Private Function GetImageFromByteArray(ByVal picData As Byte()) As Image
If picData Is Nothing Then
Return Nothing
End If

' is this is an embedded object?
Dim bmData As Integer = If((picData(0) = 21 AndAlso picData(1) = 28), 78, 0)

' load the picture
Dim img As Image = Nothing
Dim ms As New MemoryStream(picData, bmData, picData.Length - bmData)
img = Image.FromStream(ms)
End Try

' return what we got
Return img

End Function

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

Panel1.Visible = False

Dim conn As New OleDbConnection
Dim DA As OleDbDataAdapter
Dim DS As New DataSet

conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=db1.mdb;User Id=admin;Password=;"

DA = New OleDbDataAdapter("Select Empty, EmptyName, Target, TargetName from PicturesDisplayed", conn)

Me.PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage

Dim oledbconnection As OleDbConnection
oledbconnection = New System.Data.OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:Documents and SettingsAdministratorDesktopdb1.mdb;Jet OLEDB:System Database=system.mdw;")

Dim command As OleDbCommand
command = New OleDbCommand("select count (*) from PicturesDisplayed", oledbconnection)
Dim count As Integer
count = command.ExecuteScalar()

Dim randomImage As New HashSet(Of Integer)
' Create a integer and new Random object
Dim intPic As Integer
Dim rand As New Random

'Pick a random number between 0 and the number of images in database
intPic = rand.Next(0, count)

PictureBox1.Height = 256
PictureBox1.Width = 256

PictureBox2.Height = 256
PictureBox2.Width = 256

Dim pic1x As Integer = _
(Me.ClientSize.Width - PictureBox1.Width) 2
Dim pic1y As Integer = _
(Me.ClientSize.Height - PictureBox1.Height) 2
PictureBox1.Location = New Point(pic1x, pic1y)

Dim pic2x As Integer = _
(Me.ClientSize.Width - PictureBox2.Width) 2
Dim pic2y As Integer = _
(Me.ClientSize.Height - PictureBox2.Height) 2
PictureBox2.Location = New Point(pic2x, pic2y)

' Now set the picturebox image equal to the image chosen from the array randomly using the random
PictureBox1.Image = GetImageFromByteArray(DS.Tables(0).Rows.Item(intPic).Item(0))
PictureBox1.Visible = True
PictureBox2.Image = GetImageFromByteArray(DS.Tables(0).Rows.Item(intPic).Item(2))
PictureBox2.Visible = False

If (randomImage.Count = count) Then
End If

End Sub

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Nov 30, 2010

how can we or can we import data from PC RAM, and stored it to data like text or grafik...

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Dec 12, 2010

I'm am trying to determine the total number of fields under a particular heading given that the other Heading's total number of fields are > or < than the heading in question. The query, shown first in the attached code, works well if there is one column in one database table, however it does not work well when there are a number of columns with a different number of fields respectively. The CategoriesID encompasses the entire tables contents.I devised a function to determine the total number of fields within a particular column and then attempted to incorporate this, without success, into the second query, shown in the code.

Private Sub GetRandomHeadingFields()
Dim varNumberHigh As Integer
varNumberHigh = TotalNumberofHeadingFields()


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Dec 24, 2011

I have a flat file that is sorted by account number. I am migrating an application that was in vb6 to .Net. The application uses Random file access and uses a binary sort method to find a record.

Here is the code
Do While (low < high Or low = high) And (f = 0) 'Checking for an account match
middle = (low + high) / 2
FileGet(FileNum, Record, middle)
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[Code] .....

From reading up on this in .Net it seems that using the Binary Reader seek method would be the alternative to using old vb6 random access code. The problem is the Binary Reader Seek method goes by Byte position instead of record number. How to convert my code to use a binary reader.

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Imports Reader = System.IO.MyStreams
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Public Class Rec
Dim location As String = "C:\DONT DELETE ME\"
Dim int As String = 1


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