[RESOLVED] Simple yet important question

[bergerkiller]

Hello everyone.

I am currently working on my own "Colored textbox control" which inherits from the RichTextBox. What does the "Lines" property do? Does it generate the return array internally, or is it just passing back an array that is internally stored?

E.g. I use this:

    Public Sub SelectLines(ByVal lineindex As Integer, Optional ByVal linecount As Integer = 1)
        Dim lines() As String = Me.Lines
        If lineindex > lines.Count - 1 Then lineindex = lines.Count - 1
        If lineindex + linecount > lines.Count Then linecount = lines.Count - lineindex

        Dim selstart As Integer = 0
        Dim sellength As Integer = 0
        For i As Integer = 0 To lineindex + linecount - 1
            If i < lineindex Then selstart += lines(i).Length + 1 Else sellength += lines(i).Length + 1
        Next
        If sellength > 0 Then sellength -= 1
        Me.SelectionStart = selstart
        Me.SelectionLength = sellength
        Me.Focus()
    End Sub

Can I skip the generation of "lines" and just use Me.Lines(i) etc. everywhere?

The reason I ask is that I want to minimize the lag of the control, and I have to read all or a range of lines fairly commonly.

[jmcilhinney]

The Lines property generates a new array each time it is accessed. This is easy to confirm for yourself:

If myRichTextBox.Lines Is myRichTextBox.Lines Then
    'The same object is used both times.
Else
    'A new object is used each time.
End If

[bergerkiller]

Aw yeah forgot that value returning properties return a reference to the array, thanks jm.

That'll be storing the lines in a variable and updating it on each text change.