Question

I am trying to find words and replace them using regex. I keep getting a stack overflow exception, I am geussing is due to a recursive loop. So I tried removing the for loop from the first block of code, and came up with the second block of code and still the same issue.

I am trying to find certain strings while ignoring case and automatically replace them with the right case of the same string. So an example would be that someone types in “vB” it would automatically replace it with “vb”. I know my issue has to due with being in the textchanged event so if someone could guide me in the right direction I would be very thankful.

Private Sub tb_textchanged(ByVal sender As System.Object, ByVal e As    TextChangedEventArgs)

    Dim pattern As String = "\<vb\>"
    Dim input As String = txt.Text
    For Each m As Match In Regex.Matches(input, pattern, RegexOptions.IgnoreCase)
        Dim caretpos As FastColoredTextBoxNS.Place = New Place(txt.Selection.Start.iChar, txt.Selection.Start.iLine)
        Dim replacement As String = "<vb>"
        Dim rgx As New Regex(pattern)
        Dim result As String = rgx.Replace(input, replacement, RegexOptions.IgnoreCase)
        txt.Text = result
        txt.Selection.Start = New Place(caretpos.iChar, caretpos.iLine)
    Next

End Sub

After replacing the For loop.

Private Sub tb_textchanged(ByVal sender As System.Object, ByVal e As TextChangedEventArgs)

    Dim pattern As String = "\<vb\>"
    Dim input As String = txt.Text
    Dim matches As MatchCollection = Regex.Matches(input, pattern, RegexOptions.IgnoreCase)
    If matches.Count > 0 Then
        Dim caretpos As FastColoredTextBoxNS.Place = New Place(txt.Selection.Start.iChar, txt.Selection.Start.iLine)
        Dim replacement As String = "<vb>"
        Dim rgx As New Regex(pattern)
        Dim result As String = rgx.Replace(input, replacement, RegexOptions.IgnoreCase)
        txt.Text = result
        txt.Selection.Start = New Place(caretpos.iChar, caretpos.iLine)
    End If

End Sub

Answer 1

Private isRecursive As Boolean
Private Sub tb_textchanged(ByVal sender As System.Object, ByVal e As TextChangedEventArgs)

    If (isRecursive) Then
        Return
    End If
    isRecursive = True

    Dim pattern As String = "\<vb\>"
    Dim input As String = txt.Text
    Dim matches As MatchCollection = Regex.Matches(input, pattern, RegexOptions.IgnoreCase)
    If matches.Count > 0 Then
        Dim caretpos As FastColoredTextBoxNS.Place = New Place(txt.Selection.Start.iChar, txt.Selection.Start.iLine)
        Dim replacement As String = "<vb>"
        Dim rgx As New Regex(pattern)
        Dim result As String = rgx.Replace(input, replacement, RegexOptions.IgnoreCase)
        txt.Text = result
        txt.Selection.Start = New Place(caretpos.iChar, caretpos.iLine)
    End If

    isRecursive = False
End Sub