VB.NET - How to delete multiple consecutive lines in a text file? - vb.net

Question

I am making a customer management system for a school project and I need to be able to delete customers.
Each customer takes up 8 lines in the text file.
I have got it to delete one line using:
Dim lines() As String
Dim outputlines As New List(Of String)
Dim searchstring1 As String = lblName.Text
lines = IO.File.ReadAllLines("Customers.text")
For Each line As String In lines
If line.Contains(searchstring1) = False Then
outputlines.Add(line)
FileClose(1)
System.IO.File.Delete("Customers.text")
IO.File.WriteAllLines("Customers.text", outputlines)
FileClose(1)
End If
Next
But I'm not sure how to repeat this another 7 times, any ideas?

Answer 1

Instead of the for-each-loop, I would use a classical for-next, with a step of 8 - If we can be sure that each dataset consists of 8 lines, and the searchstring is found in the first:
...
For LineNo As Integer=0 to lines.count()-1 step 8
If lines(LineNo).Contains(searchstring1) = False
...
End If
Next lineNo
Additionally, you should close the input file directly after reading before going into the for-loop, and you should probably write the outputlines only after the for-next-loop is done, otherwise you will remove all customers after the searched one.
Next step is to check for errors which may occur during file operations...

Answer 2

If your file has mixed format and cannot use Step 8 because it not contains only N-8-rows of data, you can use a counter.
Set it to 8 when find customer and decrement it each loop.
The creation of new line in output file will be only when counter = 0.
Dim countMatchingLines As Integer = 0
For Each line As String In lines
If line.Contains(searchstring1) Then
countMatchingLines = 8
End If
If countMatchingLines = 0 Then
outputlines.Add(line)
FileClose(1)
System.IO.File.Delete("Customers.text")
IO.File.WriteAllLines("Customers.text", outputlines)
FileClose(1)
Else
countMatchingLines -= 1
End If
Next
Another solution, is just skip next 8 lines by manipulation for-var-counter:
For i as Integer = 0 to lines.Count() - 1
If line.Contains(searchstring1) Then
i = Math.Min(i + 8, lines.Count()-1)
Else
outputlines.Add(line)
FileClose(1)
System.IO.File.Delete("Customers.text")
IO.File.WriteAllLines("Customers.text", outputlines)
FileClose(1)
End If
Next
It will avoid necessary iterates and Ifs..

Answer 3

Try This...
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Label1.Text = RemoveParagraphOfText("GARBAGE RECORD", Line)
End Sub
Public Function RemoveParagraphOfText(ByVal textTobeRemoved As String, ByVal Message As String) As String
RemoveParagraphOfText = Message.Replace(textTobeRemoved, "")
End Function