loop over all textboxes in a form, including those inside a groupbox
If you don't care about the order (and I can't imagine a reason why you should) of the controls, you can do this iteratively in the following fashion (its quite straightforward, so I don't think any explanation is necessary). Should be much more efficient than any recursion, especially if you have many nested controls, though I doubt if the performance gain would be apparent.
Public Function FindAllControlsIterative(ByRef parent As Control) As List(Of TextBox)
Dim list As New List(Of TextBox)
Dim ContainerStack As New Stack(Of Control)
ContainerStack.Push(parent)
While ContainerStack.Count > 0
For Each child As Control In ContainerStack.Pop().Controls
If child.HasChildren Then ContainerStack.Push(child)
If child.GetType Is GetType(TextBox) Then list.Add(child)
Next
End While
Return list
End Function
You'd want to do recursion, for example (pseudocode, since I do not know VB):
Sub LoopControls (Control Container)
if (Container has Controls)
LoopControls(Container)
For Each c As Control In Container
if (Control is TextBox)
// do stuff
End Sub
You would pass your form (me) to the sub initially, and it will traverse the controls in it looking for ones that contain more controls.
Also check out this question: VB.NET - Iterating through controls in a container object
You can use this function, linq might be a more elegant way.
Dim allTxt As New List(Of Control)
For Each txt As TextBox In FindControlRecursive(allTxt, Me, GetType(TextBox))
'....'
Next
Public Shared Function FindControlRecursive(ByVal list As List(Of Control), ByVal parent As Control, ByVal ctrlType As System.Type) As List(Of Control)
If parent Is Nothing Then Return list
If parent.GetType Is ctrlType Then
list.Add(parent)
End If
For Each child As Control In parent.Controls
FindControlRecursive(list, child, ctrlType)
Next
Return list
End Function