Visual Basic

Public Class Form1


  Const NumberOfDaystocountBack = 4 'This is a constant for the number of dats you will count back
  Dim OriginalDataArray(15, 5) As String 'This is a sample array with 15 records each with 5 pieces of data
  Dim ResultsArray(1, 1) As String 'This is a sample array that will store the data, it is resized with the code

  Private Sub Main()
    'Generate test data
    Dim X As Integer
    Dim Y As Integer
    Dim TempString As String
    For X = 15 To 0 Step -1
      TempString = ""
      For Y = 0 To 4
        OriginalDataArray(X, Y) = Int(Rnd() * 10)
        TempString = TempString & OriginalDataArray(X, Y).ToString & ", "
      Next
      ListBox1.Items.Add(TempString)
    Next

    GenerateResults()

    For X = 15 To 0 Step -1
      TempString = ""
      For Y = 0 To 3

        TempString = TempString & ResultsArray(X, Y).ToString & ", "
      Next
      ListBox2.Items.Add(TempString)
    Next


  End Sub

  Private Sub GenerateResults()
    Dim MaxDayCount As Long
    Dim LoopCounter As Integer
    Dim RecordLoopCounter As Long
    Dim DataLoopCounter As Long
    Dim DataCount As Integer 'count of the number of data elements

    Dim TempArray1() As Integer
    Dim TempArray2() As Integer

    DataCount = OriginalDataArray.GetUpperBound(1) 'This will be '5' for the sample array given
    MaxDayCount = OriginalDataArray.GetUpperBound(0)  'This would be 50 for the sample array given

    ReDim ResultsArray(MaxDayCount, NumberOfDaystocountBack) 'Resize the results array to accept data


    For RecordLoopCounter = MaxDayCount To 0 Step -1 'Steps back through records of data

      'Pass the two days data to the comparison function
      For DataLoopCounter = 1 To NumberOfDaystocountBack

        ReDim TempArray1(DataCount) 'Resize array to the number of data elements and clears data
        ReDim TempArray2(DataCount) 'Resize array to the number of data elements and clears data
        If RecordLoopCounter - DataLoopCounter >= 0 Then
          For LoopCounter = 0 To DataCount - 1
            'Creates two temporary arrays that hold the data for the two days in question
            TempArray1(LoopCounter) = OriginalDataArray(RecordLoopCounter, LoopCounter)
            TempArray2(LoopCounter) = OriginalDataArray(RecordLoopCounter - DataLoopCounter, LoopCounter)
          Next

          ResultsArray(RecordLoopCounter, DataLoopCounter - 1) = CompareTwoDays(TempArray1, TempArray2)

        Else
          ResultsArray(RecordLoopCounter, DataLoopCounter - 1) = "-"

        End If

      Next

    Next

  End Sub




  Private Function CompareTwoDays(ByVal TodayArray() As Integer, ByVal CompareDayArray() As Integer) As Integer
    Dim TodayArraySize As Integer
    Dim LoopCounter As Integer
    Dim TempCount As Integer

    If TodayArray.GetUpperBound(0) <> CompareDayArray.GetUpperBound(0) Then
      'Put your error handling here
      MsgBox("Cannot compare arrays of different sizes.", MsgBoxStyle.Critical, "Error")
      End
    End If


    TodayArraySize = TodayArray.GetUpperBound(0)
    'Loop through array to compare values
    For LoopCounter = 0 To TodayArraySize - 1
      If TodayArray(LoopCounter) = CompareDayArray(LoopCounter) Then TempCount = TempCount + 1 'or you can use TempCount+=
    Next

    Return TempCount

  End Function



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

Private Sub btnNewFolder_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnNewFolder.Click
    If Not SelectedPath Is Nothing Then
        Dim NewPath As String = InputBox("New Folder:", "Create Folder")
        If NewPath <> "" Then
            'Dummy
            MsgBox(String.Format("Folder {0} has been created", NewPath))
        End If
    Else
        MsgBox("A path has to be marked!", MsgBoxStyle.Exclamation, "Error")
    End If
End Sub

Private Sub btnCancel_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCancel.Click
    DlgResult = False
    Me.Close()    'supposed to close frmFolderBrowser
End Sub

Private Sub frmFolderBrowser_FormClosed(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
    frmCenter.Refresh()
End Sub

Michael Schäuble wrote:

How can I change this behaviour?

captainmogo wrote:

If the database in unreachable - I want to wait and then try again but if there is a problem with the retrieved data, I want to send it up to the calling code

Luc Pattyn wrote:

. when you want retries, you can but the try-catch inside the loop and swallow exceptions in all but the last iteration. Don't retry forever.

3. background threads typically need to report back to their parent thread, whether success or failure. You shouldn't have a background thread retry forever, or just fail or give up without telling.

for (int tryCount=1; ; tryCount++) {
    try {
        ...
    } catch(Exception exc) (
        if (tryCount< maxTry) continue;
        log(exc.ToString());
        throw new ApplicationException("Operation XXX failed after "+maxTry+" tries", exc);
    }
}
// getting here on success only