How can I append a string that contains "" to an existing string in VB .NET? - vb.net

Question

I am working on a utility that will take the contents of a .ps1 script (Powershell), and run it in the context of a VB.NET Winform. Basically it does this by referencing some Powershell DLLs, opening the .ps1 file, reading a line of text and feeding it into an internal string that will run on a button click event.
Here's the full code I have so far:
Private Function RunScript(ByVal scriptText As String) As String
' create Powershell runspace
Dim MyRunSpace As Runspace = RunspaceFactory.CreateRunspace()
' open it
MyRunSpace.Open()
' create a pipeline and feed it the script text
Dim MyPipeline As Pipeline = MyRunSpace.CreatePipeline()
MyPipeline.Commands.AddScript(scriptText)
' add an extra command to transform the script output objects into nicely formatted strings
' remove this line to get the actual objects that the script returns. For example, the script
' "Get-Process" returns a collection of System.Diagnostics.Process instances.
MyPipeline.Commands.Add("Out-String")
' execute the script
Dim results As Collection(Of PSObject) = MyPipeline.Invoke()
' close the runspace
MyRunSpace.Close()
' convert the script result into a single string
Dim MyStringBuilder As New StringBuilder()
For Each obj As PSObject In results
MyStringBuilder.AppendLine(obj.ToString())
Next
' return the results of the script that has
' now been converted to text
Return MyStringBuilder.ToString()
End Function
' helper method that takes your script path, loads up the script
' into a variable, and passes the variable to the RunScript method
' that will then execute the contents
Private Function LoadScript(ByVal filename As String) As String
Try
' Create an instance of StreamReader to read from our file.
' The using statement also closes the StreamReader.
Dim sr As New StreamReader(filename)
' use a string builder to get all our lines from the file
Dim fileContents As New StringBuilder()
' string to hold the current line
Dim curLine As String = ""
' loop through our file and read each line into our
' stringbuilder as we go along
Do
' read each line and MAKE SURE YOU ADD BACK THE
' LINEFEED THAT IT THE ReadLine() METHOD STRIPS OFF
curLine = sr.ReadLine()
If curLine.Contains("") Then
fileContents.AppendLine("$Folder=tbpath.selectedpath")
Else
fileContents.Append(curLine + vbCrLf)
If curLine.Contains ($Folder="") Then
Loop Until curLine Is Nothing
' close our reader now that we are done
sr.Close()
' call RunScript and pass in our file contents
' converted to a string
Return fileContents.ToString()
Sorry for the lengthy stuff, but the lines I am curious about are the curLine.Contains part. What I'm trying to do is have the parser detect whether or not the line is a specific one (which reads $Folder = "") and replace the empty quotes with a folder path that is stored in a text box (tbpath.selectedtext). Unfortunately, since the Powershell script requires quotes around the path string (in case there are spaces) I am having trouble figuring out how to do what I want it to do.
What should I do there? Should I build what I want into a new variable (maybe vbPath = tbpath.selectedtext) and put it into the new line? Are there any "best practices"?

Answer 1

Double up the quotes
Dim s As String = "$Folder = """""
s =
$Folder = ""
In your code
If curLine.Contains("$Folder = """"") Then
End If

Answer 2

Do you want curLine.Contains() to check for a literal string $Folder=""? If so, you need to put the whole string in double quotes and escape the inner ones. Double quotes are escaped by doubling them. Also, if you want to insert a variable, you need to concatenate it with the string literals, so the command should probably look like this:
If curLine.Contains ("$Folder = """"") Then
fileContents.Append("$Folder = """ & tbpath.selectedpath & """")
End If