VB.net Index was out of range?

Hey guys,

I can't figure out why I am getting this error? Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: Index VS2010 VB.net

      Dim RC As Integer = dgv_POSData.RowCount
        Dim i As Integer = 0
        txt_Log.Text = txt_Log.Text & "OpenDates " & lbl_SrchStartDate.Text & " and " & lbl_SrchEndDate.Text & vbCrLf
        txt_Log.Text = txt_Log.Text & "Verifying " & RC & " rows" & vbCrLf

        Do While i <= RC
            'MessageBox.Show(i)

            Dim HN As String = dgv_POSData.Rows(i).Cells(2).Value
            Dim DN As String = dgv_POSData.Rows(i).Cells(3).Value
            Dim HF As String = dgv_POSData.Rows(i).Cells(4).Value
            Dim HPF As String = dgv_POSData.Rows(i).Cells(5).Value

            If HN - DN = 0 Then
                txt_Log.Text = txt_Log.Text & "Trans " & dgv_POSData.Rows(i).Cells(1).Value & " Header vs Detail = Good" & vbCrLf
            Else
                Dim RD As Double = HN - DN
                txt_Log.Text = txt_Log.Text & "Trans " & dgv_POSData.Rows(i).Cells(1).Value & " Header vs Detail difference of " & RD & vbCrLf
            End If

            If HF - HPF = 0 Then
                txt_Log.Text = txt_Log.Text & "Trans " & dgv_POSData.Rows(i).Cells(1).Value & " Header vs HowPaid = Good" & vbCrLf
            Else
                Dim RD As Double = HF - HPF
                txt_Log.Text = txt_Log.Text & "Trans " & dgv_POSData.Rows(i).Cells(1).Value & " Header vs HowPaid difference of " & RD & vbCrLf
            End If


            i = i + 1
        Loop

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For testing I added a messagebox to show me the value of i. If I uncomment MessageBox.Show(i) it works and fails on the last row of the datagrid, but if I comment it out, it fails on the very first row? I don't understand what displaying the value of i has to do with anything?

What am I missing? Am I going crazy?
triphenAsked:
Who is Participating?
 
Fernando SotoRetiredCommented:
It looks like you are off by one. RC is the total row count and index starts at 0 and not 1 so you should iterate to 1 less then RC as shown below.

Do While i < RC
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triphenAuthor Commented:
That may have worked, but now I have another problem with my SQL it looks like be right back :)
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it_saigeDeveloperCommented:
*No points*

Just to illustrate what Fernando has stated.  Say I have a collection (or an array) of 5 items.

The count property will return 5.
But the items in the collection/array are accessible by their index.
Arr[0]
Arr[1]
Arr[2]
Arr[3]
Arr[4]

Five items but no index for 5.  So when iterating over a collection based on the count you want to use either count - 1; e.g. -
Module Module1
	Sub Main()
		Dim Arr(4) As Integer
		For i As Integer = 0 To 4
			Arr(i) = i
		Next

		Console.WriteLine("Array Count is {1};{0}Array Length is {2};{0}Array Lower Bounds is {3};{0}Array Upper Bounds is {4};", Environment.NewLine, Arr.Count, Arr.Length, Arr.GetLowerBound(0), Arr.GetUpperBound(0))
		Dim j As Integer = 0
		While (j <= Arr.Count - 1)
			Console.WriteLine("Array Index {0}; contains {1}", j, Arr(j))
			j = j + 1
		End While
		Console.ReadLine()
	End Sub
End Module

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Or the count explicitly -
Module Module1
	Sub Main()
		Dim Arr(4) As Integer
		For i As Integer = 0 To 4
			Arr(i) = i
		Next

		Console.WriteLine("Array Count is {1};{0}Array Length is {2};{0}Array Lower Bounds is {3};{0}Array Upper Bounds is {4};", Environment.NewLine, Arr.Count, Arr.Length, Arr.GetLowerBound(0), Arr.GetUpperBound(0))
		Dim j As Integer = 0
		While (j < Arr.Count)
			Console.WriteLine("Array Index {0}; contains {1}", j, Arr(j))
			j = j + 1
		End While
		Console.ReadLine()
	End Sub
End Module

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Both of the code examples above produce the following output -Capture.JPG-saige-
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