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What is the reverse to this code? - Reading and writing between Text file and DataView/DataSet

The following code sucessfully creates and writes the contents of a DataView (each value seperated by '#') to a Text file. Please can someone give me the code that will correctly read it back?

Private Sub SaveDBToFile()
Dim path As String = "C:\Temp\MyFile.txt"

'Create the file.
Dim fs As FileStream = File.Create(path)

Dim myDRV As DataRowView
For Each myDRV In MyDataView
For i As Integer = 0 To MyDataView.Table.Columns.Count - 1
If (Not (myDRV(i) Is DBNull.Value)) Then
AddText(fs, CType(myDRV(i), String) + "#")
Else
AddText(fs, " #")
End If
Next
AddText(fs, Environment.NewLine)
Next
fs.Close()
End Sub

Private Shared Sub AddText(ByVal fs As FileStream, ByVal value As String)
Dim info As Byte() = New UTF8Encoding(True).GetBytes(value)
fs.Write(info, 0, info.Length)
End Sub

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Ramuncikas

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IvanHowarth

ASKER

The first half of your code throws a complete wobbly :(

The following error message keeps recurring (regardless if it's in a try-catch statement) and can only be stopped by killing the process via task manager:

System.IO.IOException: The process cannot access the file "C:\Temp\MyTest.txt" because it is being used by another process.
at System.IO._Error.WinIOError(Int32 errorCode, String str)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize,
Boolean useAsync, String msgPath, Boolean bFormProxy)
at System.IO.Stream..ctor(String path, FileMode mode)
at [MyApp]

(path is a variable containing the path of the file)

Any ideas?

IvanHowarth

ASKER

Disregard the above error message, I have now moved the method call as the first line to avoid any conflict.
Nevertheless, I do get the following problem:

System.ArgumentNullException: Buffer cannot be null.
Parameter name: array
at System.IO.FileStream.Read(Byte[]array,Int32 offset, Int32 count)
...

Re wrote your array declaration to:

Dim bytes(CInt(fs.Length - 1)) As Byte

and then you get:

System.IndexOutOfRangeException: Cannot find column 34.
at System.DataColumnCollection.get_Item(Int32 index)
at System.Data.DataRow.set_Item(Int32 columnIndex, Object value)
...

34 columns was written to file. fs.Length gives a value of 304229

IvanHowarth

ASKER

Problem found....

In my original code [AddText(fs, CType(myDRV(i), String) + "#") ] appended the # to the last column. Your code then looked for another column after this that didn't exist. I slightly modified your code so it didn't read that far:

sCols = Line1.Split(CChar("#"))
For y As Integer = 0 To sCols.Length - 2
...
Next