Option Explicit On
Option Strict On

Public Class MainForm

    Public filecontents As String

    Private Sub MainForm_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        ' load from the text file the product item numbers nad prices

        ' declare the variables used
        Dim inputfile As String = "C:\Visual Studio 2005\Projects\SummarizeExports\SummarizeExports\bin\Debug\Exports.txt"



        ' check to make sure the file exists, and if yes then
        ' get the contents of the file. If not, display message.

        If My.Computer.FileSystem.FileExists(inputfile) Then
            filecontents = My.Computer.FileSystem.ReadAllText(inputfile)

            Call Process_Export_File()

        Else
            MessageBox.Show("File does not exist", "Exports.txt", _
                MessageBoxButtons.OK, MessageBoxIcon.Information)

        End If



        ' close the application
        Me.Close()

    End Sub

    Private Sub Process_Export_File()
        ' dimension array to store each line in the Exports.txt file


        Dim counter As Integer = 0
        Dim lineindex As Integer
        Dim transaction() As String = Split(filecontents, vbCrLf)
        Dim cost(lineindex) As String
        Dim client(lineindex) As String
        Dim duplicating As String = "Duplicating"
        Dim position As Integer = 1
        Dim newposition As Integer


        ' find first newline in string
        lineindex = filecontents.IndexOf(ControlChars.NewLine)

        ' run through data to store each transaction in the transaction array
        Do Until lineindex - counter <= 0
            position = transaction(counter).IndexOf("Duplicating", 0)
            newposition = position + 11

            ' get the cost value of the transaction
            cost(counter) = transaction(counter).Substring(1, position)
            cost(counter) = cost(counter).Trim

            ' get the client number for the transaction
            client(counter) = transaction(counter).Substring(newposition, 6)
            client(counter) = client(counter).Trim

            Const File As String = "TestExport.txt"
            My.Computer.FileSystem.WriteAllText(File, _
            cost(counter) & _
            " " & duplicating & _
            " " & client(counter) & _
            ControlChars.NewLine, True)

            ' update the counter and loop
            counter = counter + 1


        Loop
    End Sub

End Class

Dim cost(lineindex) As String
Dim client(lineindex) As String

    Private Sub Process_Export_File()
        Const File As String = "TestExport.txt"

        Dim accountCode As String
        Dim cost As Decimal
        Dim fields() As String
        Dim fileData As ArrayList = New ArrayList
        Dim lineContent As String
        Dim name As String
        Dim reorderedLine As String
        Dim transaction() As String = Split(filecontents, vbCrLf)

        For Each lineContent In transaction
            'ignore blank lines
            If lineContent.Length = 0 Then
                Continue For
            End If
            'split the line into it's fields: cost, name, code
            fields = Split(lineContent, vbTab)
            'reverse the field order so account code is first
            reorderedLine = fields(2) & vbTab & fields(1) & vbTab & fields(0)
            'add to list
            fileData.Add(reorderedLine)
        Next
        ' sort the list, multiple account codes will now be grouped together
        fileData.Sort()
        'copy the first string in the list
        reorderedLine = fileData.Item(0).ToString()
        'split it back to fields
        fields = Split(reorderedLine, vbTab)
        'save the individual items
        accountCode = fields(0)
        name = fields(1)
        cost = 0
        'loop on the arraylist contents
        For Each reorderedLine In fileData
            'back to fields
            fields = Split(reorderedLine, vbTab)
            'if this line has the same account code, add the cost to running total
            If fields(0) = accountCode Then
                cost += Decimal.Parse(fields(2))
            Else
                'save the previous account code information
                lineContent = accountCode + vbTab + name + vbTab + cost.ToString() + vbNewLine
                'write line to file, appending it
                My.Computer.FileSystem.WriteAllText(File, lineContent, True)
                'save current information
                accountCode = fields(0)
                name = fields(1)
                cost = Decimal.Parse(fields(2))
            End If

        Next
        'save the last account code information
        lineContent = accountCode + vbTab + name + vbTab + cost.ToString() + vbNewLine
        'write line to file, appending it
        My.Computer.FileSystem.WriteAllText(File, lineContent, True)

    End Sub

  reorderedLine = fields(2) & vbTab & fields(1) & vbTab & fields(0)

...
//'split the line into it's fields: cost, name, code
fields = Split(lineContent, vbTab)
//'All three tokens present?
if fields.Length() = 3 then
    //'reverse the field order so account code is first
    reorderedLine = fields(2) & vbTab & fields(1) & vbTab & fields(0)
    //'add to list
    fileData.Add(reorderedLine)
Else
    //'Bad data
    MessageBox.Show("Bad data line - " + lineContent)
End If
...