displaying info within a loop

hscorpio · #1 (**permalink**) 12-02-2008, 2:48 PM

Hi all

Can I please get some help on some basic coding.

The user Pushes a button on the form.
A 'For loop' begins at i=0
Textbox2 is set to display some information within the loop
Then it goes onto the next i. Again Textbox2 displays new information.

How do you go about doing this?

Many Thanks
Hscorpio

JuggaloBrotha · #2 (**permalink**) 12-02-2008, 2:59 PM

How hard is it to set the text property of a textbox from code? Me.Textbox1.Text = "Some text"

You can do that from within a loop too.

hscorpio · #3 (**permalink**) 12-02-2008, 3:56 PM

Not hard at all if you know the answer. I guess thats why I asked.

But you'll have to dumb it down a bit more for me.

for i = 0 to x
me.textbox2.text=textbox2.text & " " & aa(i)
next i

gives me the same result as I had before I added the me. windows form bit. It goes through the loop and the user only sees what comes out at the end.

MattP · #4 (**permalink**) 12-02-2008, 6:35 PM

Code:

	Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _
	Handles MyBase.Load

		Me.BackgroundWorker1.WorkerReportsProgress = True
		Me.BackgroundWorker1.RunWorkerAsync()

	End Sub

	Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) _
	Handles BackgroundWorker1.DoWork

		For i As Integer = 0 To 10000
			BackgroundWorker1.ReportProgress(i / 100, i)
			Threading.Thread.Sleep(1)
		Next

	End Sub

	Private Sub BackgroundWorker1_ProgressChanged(ByVal sender As System.Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) _
	Handles BackgroundWorker1.ProgressChanged

		Me.lblUserState.Text = "Number: " & e.UserState.ToString()
		Me.lblPercent.Text = e.ProgressPercentage.ToString() & "%"

	End Sub

Solitaire · #5 (**permalink**) 12-02-2008, 9:58 PM

The following works for me:

Dim aa() As Integer = {2, 4, 6, 8, 10}
For i As Integer = 0 To 4
TextBox2.Text &= aa(i) & " "
Next

cjard · #6 (**permalink**) 12-03-2008, 7:11 AM

Quote:

Originally Posted by Solitaire

The following works for me:

But, it doesnt work for the OP

He wants to count to.. say.. a million.. And he wants to see the numbers rolling up in the text box from 1 to a million (or the text extending each time). He does not want to click the Go button, and have the UI hang for 30 seconds while VB concatenates a million strings together and stores them in a text box and only reveals the result at the end, hence why MattP provided the BackgroundWorker example

hscorpio: note that MattP's example replaces the text each time. If you want to append the text each time, use textbox.AppendText("text") in place of textbox.Text = "text"

Note also that you DONT have to use e.ProgressPercentage (you can set it to 0 always, or use it to pass status codes) nor does it have to be a progress percentage at all; it can jump up and down and be totally unrelated to your operation's progress.
You can pass any information you like in the UserState parameter; MattP passes a number, i, but it can be a string, number, error, anything. At the other side, in the ProgressChanged event handler, convert the userstate back to what you want with DirectCast(e.UserState, <type>).
e.g. Suppose you had a custom class ReportState, you would

Code:

Dim myReportState as New ReportState
...
BackgroundWorker1.ReportProgress(i / 100, myReportState)

...
'and in the progress changed event handler:

...
Dim tmpRepState as ReportState = DirectCast(e.UserState, ReportState)
'now do whatever you want with the reportstate object

As an example, when using a background worker, i'll use the progress percentage as the level of logging from 0 to 5 (low to high) and the userstate as the message i want to log. You can also use the TypeOf() command to see what kind of object the UserState is, and perform different actions depending on what it is

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