Question

I am running a index search on a string in a rich textbox, i have a list of keywords which need to be a different color in this textbox. how do i run a search on a string in vb2005 and get a list of indexes where the text matched my search?

Answer 1

Here is a fairly simple solution. Note that it will find the word “our” in “Four”. If that is not desirable you can write something to eliminate overlapping matches.

Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Dim SearchText As String = "One Two Three Four"

    Dim Keywords As String() = {"One", "Four", "our"}

    Dim WordMatches As New Generic.List(Of WordMatch)

    For Each KeyWord As String In Keywords
        Dim i As Int32 = 0

        While i <> -1
            i = SearchText.IndexOf(KeyWord, i, System.StringComparison.OrdinalIgnoreCase)

            If i <> -1 Then
                Dim MyMatch As New WordMatch
                MyMatch.CharIndex = i
                MyMatch.Word = KeyWord
                WordMatches.Add(MyMatch)
                i += KeyWord.Length
            End If
        End While
    Next
End Sub

Private Structure WordMatch
    Public CharIndex As Int32
    Public Word As String
End Structure