Loop through Controls in .NET

Posted on 2003-10-28
Last Modified: 2010-05-01
You would think this would be the easiest task to do in VB .Net, but the old way of doinf thinsg does not seem to work
And do you reckon I can find it anywhere on the Microsoft Site?

Can someone tell me how I loop through all Textboxes on a Form to simply empty them.
The textboxes are inside a TabPage

Question by:wlawson
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Expert Comment

ID: 9639216
I just recently had to loop through all the controls on a form for something.

This is just one way that you could implement this loop, this uses a recursive function.

    Public Sub DoTheLoop()
    End Sub

    Private Sub LoopThroughAllControls(ByVal controls As ControlCollection)
        Dim c As Control
        For Each c In controls
            If GetType(TextBoxBase).IsInstanceOfType(c) Then
                ' c is a textbox based control, do something with it
            End If
            ' loop through sub controls
    End Sub

Author Comment

ID: 9639282
Thanks for that it works well for all Controls on the actual form, but it will not work for anything within the TabPage Control.


Author Comment

ID: 9639341
I can see what your code is trying to do and if feed the TabControl into your Sub Rountine I can count the Controls on the page, but when I try to loop through the controls I get an error "Specific Cast is not valid"

Accepted Solution

bacon7181 earned 50 total points
ID: 9642965
Try this one:

    Private Sub LoopThroughAllControls(ByVal parentControl As Control)
        Dim c As Control

        ' Make sure there are children to iterate over
        If Not c.HasChildren Then
        End If

        For Each c In parentControl.Controls
            ' Find children of desired type
            If GetType(TextBox).IsInstanceOfType(c) Then
                ' c is a textbox based control, do something with it
                c.Text = "Howdy"
            End If
            ' If this control also has children
            If c.HasChildren Then
                ' loop through sub children
            End If
    End Sub

Author Comment

ID: 9646597
Top Shelf ... Worked a treat

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