Select block of text and merge into new document - regex

Question

Hi I've looked online and just can't find the right answer. I have files which have <!--#start#--> and <!--#stop#--> through out them.
I only want the contents between those two strings. The code I have still prints out all the data including the start/stop lines.
Dim Prefix As String
Dim newMasterFilePath As String
Dim masterFileName As String
Dim newMasterFileName As String
Dim startMark As String = "<!--#start#-->"
Dim stopMark As String = "<!--#stop#-->"
'values from GUI form
searchDir = txtDirectory.Text
Prefix = txtBxUnique.Text
For Each singleFile In allFiles
If File.Exists(singleFile.FullName) Then
Dim fileName = singleFile.FullName
Debug.Print("file name : " & fileName)
' A backup first
Dim backup As String = fileName & ".bak"
File.Copy(fileName, backup, True)
' Load lines from the source file in memory
Dim lines() As String = File.ReadAllLines(backup)
' Now re-create the source file and start writing lines inside a block
' Evaluate all the lines in the file.
' Set insideBlock to false
Dim insideBlock As Boolean = False
Using sw As StreamWriter = File.CreateText(backup)
For Each line As String In lines
If line = startMark Then
' start writing at the line below
insideBlock = True
' Evaluate if the next line is <!Stop>
ElseIf line = stopMark Then
' Stop writing
insideBlock = False
ElseIf insideBlock = True Then
' Write the current line in the block
sw.WriteLine(line)
End If
Next
End Using
End If
Next
Here in another part of my code I'm grabbing the entity name from the main document and replacing it with the text between start and stop
Dim strMasterDoc = File.ReadAllText(existingMasterFilePath)
Dim newMasterFileBuilder As New StringBuilder(strMasterDoc)
'Create a regex with a named capture group.
Dim rx = New Regex("&" & Prefix & "_Ch(?<EntityNumber>\d+(?:-\d+)*)[;]")
Dim reg1 As String
reg1 = rx.ToString
Debug.Write("Chapter Entity: " & reg1)
Dim rxMatches = rx.Matches(strMasterDoc)
For Each match As Match In rxMatches
Dim entity = match.ToString
'Build the file name using the captured digits from the entity in the master file
Dim entityFileName = Prefix & $"_Ch{match.Groups("EntityNumber")}.sgm"
Dim entityFilePath = Path.Combine(searchDir, entityFileName)
'Check if the entity file exists and use its contents
'to replace the entity in the copy of the master file
'contained in the StringBuilder
If File.Exists(entityFilePath) Then
Dim entityFileContents As String = File.ReadAllText(entityFilePath)
newMasterFileBuilder.Replace(entity, entityFileContents)
End If
Next
'write the processed contents of the master file to a different file
File.WriteAllText(newMasterFilePath, newMasterFileBuilder.ToString)

Answer 1

As Mentioned in my comment i think the problem might be that the lines in lines() include the carriage return and line feed characters. have you tried to use line.Contains(startMark) instead of testing for equality?
Also; is there a specific reason that you are reading all the lines and storing them first, before looping over them to check them? I think it would be more efficient to read, check and write in one go:
Using SR As New StreamReader(YourFilePath)
Using sw As New StreamWriter(OtherFilePath)
Do Until SR.EndOfStream
line = SR.ReadLine()
If line.contains(startMark) Then
' start writing at the line below
insideBlock = True
' Evaluate if the next line is <!Stop>
ElseIf line.Contains(stopMark) Then
' Stop writing
insideBlock = False
ElseIf insideBlock = True Then
' Write the current line in the block
sw.WriteLine(line)
End If
Loop
End Using
End Using