Currently having problems with deleting/overwriting from a file - vb.net

Question

I'm currently having problems trying to delete a line from a file and replace that line with different text (overwrite the line)
The code initially starts by extracting file contents to find the
DepartmentDetails which can be used to find DepartmentBudget and subtract AmountDue and then create a new DepartmentDetails with the new budget
Once this is complete the code will add the N̳e̳w̳ DepartmentDetails which will leave the code with having the O͟l͟d͟ and the N̳e̳w̳ DepartmentDetails in the same folder.
The code should then delete the O͟l͟d͟ DepartmentDetails from the file making the N̳e̳w̳ DepartmentBudget take it's place. i.e. Overwrite the O͟l͟d͟ DepartmentDetails with the new one.
The problem is that the code does not delete the O͟l͟d͟ DepartmentBudget but adds a line space in between the O͟l͟d͟ and N̳e̳w̳ instead.
Private Sub BtnBillDept_Click(sender As Object, e As EventArgs) Handles BtnBillDept.Click
Dim DepartmentStore As New Department
Dim Order() As String = File.ReadAllLines(Dir$("OrderDetails.Txt"))
Dim OrderID As String = TxtOrderID.Text
Dim AmountDue As String = TxtAmountDue.Text
Dim DeptID As String = (Trim(Mid(Order(OrderID), 5, 4)))
Dim DepartmentDetails() As String = File.ReadAllLines(Dir$("DepartmentDetails.Txt"))
Dim DepartmentBudget As String = (Trim(Mid(DepartmentDetails(DeptID), 35, 6)))
Dim FormattedBudget As String = FormatCurrency(DepartmentBudget, 2)
Dim YesNo As String
Dim sw As New StreamWriter("DepartmentDetails.txt", True)
DepartmentBudget = FormattedBudget - AmountDue
DepartmentStore.DepartmentID = LSet(DeptID, 4)
DepartmentStore.DepartmentHead = LSet((Trim(Mid(DepartmentDetails(DeptID), 5, 20))), 20)
DepartmentStore.DepartmentName = LSet((Trim(Mid(DepartmentDetails(DeptID), 25, 10))), 10)
DepartmentStore.DepartmentBudget = LSet(DepartmentBudget, 9)
DeptID = UBound(DepartmentDetails)
DepartmentDetails(DeptID) = ""
File.WriteAllLines("DepartmentDetails", DepartmentDetails)
sw.WriteLine(DepartmentStore.DepartmentID & DepartmentStore.DepartmentHead & DepartmentStore.DepartmentName & DepartmentStore.DepartmentBudget)
sw.Close()`
'***********************Having Problems Here***********************
DepartmentDetails = File.ReadAllLines(Dir$("DepartmentDetails.Txt"))
DepartmentDetails(DeptID) = ""
File.WriteAllLines("DepartmentDetails", DepartmentDetails)
'************************Having Problems Here**************************
YesNo = MsgBox("Department has been billed. Would you like to delete the bill?", vbYesNo)
If YesNo = vbYes Then
End If
End Sub

Answer 1

Who decided that this text file would be formatted with fixed length fields? All this trimming and padding could be avoided with a simple comma delimited file or an xml file or a database where it really belongs.
Code is not tested. Comments and explanations in-line.
'I assume you have a class that looks something like this
'This uses automatic properties to save you having to
'type a getter, setter and backer field (the compiler adds these)
Public Class Department
Public Property DepartmentID As Integer
Public Property DepartmentHead As String
Public Property DepartmentName As String
Public Property DepartmentBudget As Decimal
End Class
Private Sub BtnBillDept_Click(sender As Object, e As EventArgs) Handles BtnBillDept.Click
Dim DepartmentStore As New Department
'Drag an OpenFileDialog from the ToolBox to your form
'It will appear in the lower portion of the design window
Dim MyFilePath As String = ""
OpenFileDialog1.Title = "Select OrderDetails.Txt"
If OpenFileDialog1.ShowDialog = DialogResult.OK Then
MyFilePath = OpenFileDialog1.FileName
End If
Dim Order() As String = File.ReadAllLines(MyFilePath)
'Changed data type, you use OrderID as an index for the Order array so it must be an Integer
Dim OrderID As Integer
'TryParse will check if you have a valid interger and fill OrderID variable
If Not Integer.TryParse(TxtOrderID.Text, OrderID) Then
MessageBox.Show("Please enter a valid Order ID.")
Return
End If
'EDIT per comment by Codexer
If OrderID > Order.Length - 1 Then
MessageBox.Show("Order Number is too high")
Return
End If
Dim AmountDue As Decimal
If Decimal.TryParse(TxtAmountDue.Text, AmountDue) Then
MessageBox.Show("Please enter a valid Amount Due")
Return
End If
'I hope you realize that the first index in Order is zero
'Mid is an old VB6 method around for compatibility
'Use the .net Substring (startIndex As Integer, length As Integer)
'The indexes in the string start with zero
Dim DeptID As Integer = CInt(Order(OrderID).Substring(5, 4).Trim) '(Trim(Mid(Order(OrderID), 5, 4)))
OpenFileDialog1.Title = "Select DepartmentDetails.txt"
If OpenFileDialog1.ShowDialog = DialogResult.OK Then
MyFilePath = OpenFileDialog1.FileName
End If
Dim DepartmentDetails() As String = File.ReadAllLines(MyFilePath)
Dim DepartmentBudget As Decimal = CDec(DepartmentDetails(DeptID).Substring(35, 6).Trim) '(Trim(Mid(DepartmentDetails(DeptID), 35, 6)))
'You don't need to format anything until you want to display it
'Dim FormattedBudget As String = FormatCurrency(DepartmentBudget, 2)
'A MessageBox returns a DialogResult
Dim YesNo As DialogResult
Dim sw As New StreamWriter(MyFilePath, True)
'Shorcut way to write DepartmentBudget - AmountDue
DepartmentBudget -= AmountDue
'Set the property in the class with the proper data type
DepartmentStore.DepartmentID = DeptID
'Then prepare a string for the writing to the fil
Dim PaddedID = CStr(DeptID).PadLeft(4)
'The .net replacement for LSet is .PadLeft
DepartmentStore.DepartmentHead = DepartmentDetails(DeptID).Substring(5, 20).Trim.PadLeft(20)
DepartmentStore.DepartmentName = DepartmentDetails(DeptID).Substring(25, 10).Trim.PadLeft(20)
'Set the property in the class with the proper data type
DepartmentStore.DepartmentBudget = DepartmentBudget
'Then prepare a string for the writing to the fil
Dim PaddedBudget = CStr(DepartmentBudget).PadLeft(9)
sw.WriteLine(PaddedID & DepartmentStore.DepartmentHead & DepartmentStore.DepartmentName & PaddedBudget)
sw.Close()
'***********************Having Problems Here***********************
'This is using the path from the most recent dialog
DepartmentDetails = File.ReadAllLines(MyFilePath)
'Here you are changing the value of one of the elements in the DepartmentDetails array
DepartmentDetails(DeptID) = ""
'Public Shared Sub WriteAllLines (path As String, contents As String())
'The string "DepartmentDetails" is not a path
File.WriteAllLines(MyFilePath, DepartmentDetails)
'************************Having Problems Here**************************
YesNo = MessageBox.Show("Department has been billed. Would you like to delete the bill?", "Delete Bill?", MessageBoxButtons.YesNo)
If YesNo = DialogResult.Yes Then
End If
End Sub