what am i doing wrong with this VB9 code

Question

Here's what I tried:

' now let's blink the lblSum color!
        Dim intCounter As Integer
        Do While intCounter < 20
            If lblSum.ForeColor = Color.Turquoise = True Then
                lblSum.ForeColor = Color.OrangeRed = False
            Else
                lblSum.ForeColor = Color.Turquoise = True
            End If
            Me.Refresh()
            System.Threading.Thread.Sleep(250)
            intCounter = (intCounter + 1)
        Loop

VB threw an error about overload and not being able to respond to a bol question. Fair enough. Through trial and error I dropped the = True and = False syntax and my lblSum blinked color.

Now the question is:

' now let's blink the lblSum color!
        Dim intCounter As Integer
        Do While intCounter < 20
            If lblSum.ForeColor = Color.Turquoise = True Then
                lblSum.ForeColor = Color.OrangeRed
            Else
                lblSum.ForeColor = Color.Turquoise
            End If
            Me.Refresh()
            System.Threading.Thread.Sleep(250)
            intCounter = (intCounter + 1)
        Loop

I've added = True to the first line of the selection and didn't throw an error. How come? (like I said it works with ALL = T and = F removed)

Answer 1

A statement like this

  lblSum.ForeColor = Color.OrangeRed = False

doesn't make any sense, because you are trying to combine color strucutures and boolean (true/false) values


This will work for you:

        For intCounter As Integer = 0 To 20
            lblSum.ForeColor = If(lblSum.ForeColor = Color.OrangeRed, Color.Turquoise, Color.OrangeRed)
            System.Threading.Thread.Sleep(250)
            lblSum.Refresh()
        Next

however you may want to look into a background worker or spin up a seperate thread versus sleeping the main UI thread and needing to call Refresh to update the UI.

---

Matt Kleinwaks - MSMVP MSDN Forums Moderator - www.zerosandtheone.com

Answer 2

In the line you removed the =True, you were trying to do an assignment in an inappropriate way.

You want to set the ForeColor property on the label, and its type is Color, not boolean. I realize that the syntax makes sense to you, but it does not work that way with the compiler. (In C, you can assign like types, but...even C won't let you assign two different types to a regular variable.)

True / False can be problematic in practice. False is (I believe) always zero. True is simply Not False, which is all ones, or -1 when viewed as an integer. In VB, you can safely use booleans without " = True/False", namely...

If a then

The " = True" is implied, and False will evaluate to zero, making the logic work properly.

Answer 3

You can't use an expression as a variable.   You need an additional variable to represent the state of the lamp.

Static IsTurquoise as Boolean
Dim intCounter As Integer
    Do While intCounter < 20
        If IsTurquoise = True Then
            lblSum.ForeColor = Color.OrangeRed
            IsTurquoise = False
        Else
            lblSum.ForeColor = Color.Turquoise
            IsTurQuoise = True
        End If
        Me.Refresh()
        System.Threading.Thread.Sleep(250)
        intCounter = (intCounter + 1)
    Loop

Answer 4

thanks jinzai-
You're right my logical thinking was "if not one color true then..."
 kleinma said it succcinctly-"doesn't make any sense"
thanks all!