Question

I am trying to parse junk and narrow down a bunch of text. How do I delete the current line if a does not match? I would like to remove the line entirely:

For i As Integer = 0 To RichTextBox1.Lines.Length - 1
  Dim a As String = RichTextBox1.Lines(i).ToString
  If Not a = "SaveThisLine" Then
    'delete the active line
  End If
Next

Also how would I match partially? Such as if not a = "SaveThisLine" & * (to use a wildcard).

Answer 1

I would not touch original text and rather save valid lines into a StringBuilder, so if line is valid, AppendLine to it. In the end dump back into RichTextBox1.Text using StringBuilder.ToString.

For partial match in VB.NET you can use a native Like operator:

"aaa" Like "a*"

Returns True.

Or use regular expressions:

System.Text.RegularExpressions.Regex.Match("aaa", "^a").Success

Also returns True.