Dynamic textbox add and dispose : Few text boxes not getting disposed - vb.net

Question

I am creating few text boxes in windows forms dynamically and at some point I dispose these
Dim tb1 As New TextBox 'new textbox
tb1.Name = "dtba" 'setname
tb1.Location = New Point(stx, sty) 'location of textbox
tb1.Text = arl(0) 'assigning text
tb1.Width = 80 'setting width
tb1.TabStop = False 'no tabstop
tb1.Enabled = False 'disabled
Me.Controls.Add(tb1) 'add to form
'Repeating same code for few more text boxes
Dim tb2 As New TextBox
tb2.Name = "dtbb"
tb2.Location = New Point(stx + 80, sty)
tb2.Text = arl(1)
tb2.Width = 175
tb2.TabStop = False
tb2.Enabled = False
Me.Controls.Add(tb2)
Dim tb3 As New TextBox
tb3.Name = "dtbc"
tb3.Location = New Point(stx + 255, sty)
tb3.Text = arl(2)
tb3.Width = 125
tb3.TabStop = False
tb3.Enabled = False
Me.Controls.Add(tb3)
Dim tb4 As New TextBox
tb4.Name = "dtbd"
tb4.Location = New Point(stx + 380, sty)
tb4.Text = arl(3)
tb4.Width = 100
tb4.TabStop = False
tb4.Enabled = False
Me.Controls.Add(tb4)
Problem occurring when I try to delete these text boxes. Code is
For Each cControl In Me.Controls
If (TypeOf cControl Is TextBox) Then
Dim txt As TextBox = CType(cControl, TextBox)
If txt.Name.Contains("dtb") Then
txt.Dispose()
End If
End If
Next cControl
Here the text boxes named dtba and dtbc getting deleted. But dtbb and dtbd are not getting deleted. Any help ?

Answer 1

You are editing the collection whilst looping over it. Try something like this instead:
Dim l As New List(Of Control)
For Each cControl In Me.Controls
If (TypeOf cControl Is TextBox) Then
Dim txt As TextBox = CType(cControl, TextBox)
If txt.Name.Contains("dtb") Then
l.Add(cControl)
End If
End If
Next cControl
For Each c As Control In l
c.Dispose()
Next

Answer 2

Instead utilize this:
For Each cControl In Me.Controls
If (TypeOf cControl Is TextBox) Then
Dim txt As TextBox = CType(cControl, TextBox)
If txt.Name.Contains("dtb") Then
txt.Dispose()
End If
End If
Next cControl
Do this:
Again:
For Each cControl In Me.Controls
If (TypeOf cControl Is TextBox) Then
Dim txt As TextBox = CType(cControl, TextBox)
If txt.Name.Contains("dtb") Then
Me.Controls.Remove(txt)
GoTo again
End If
End If
Next
The problem is related to INDEX of FOR EACH, that loss the pointer when the controls is deleted. You must repeat the operation to ensure a new index.