Doing without Control Arrays

The included zip file contains complete source code of a vb.net windows forms project that contains 2 command buttons and a textbox when you run it. Entering an amount of controls to create and clicking the create button adds the selected amount of command buttons and links their click event to the design time command button.

When you click any of the dynamically created buttons or the design time button the same event procedure checks to see which control was clicked and informs you.

The key parts to the source code are:-

1. The DesignTime button's click event

Private Sub cbDesignTime_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbDesignTime.Click
   'get a reference to the sender onjects name
   Dim cName As String = CType(sender, System.Windows.Forms.Button).Name
   'check to see which control was clicked by name
   If cName = "cbDesignTime" Then
      MsgBox("You clicked the Button placed here in design time")
   Else
      Dim x As Integer
      For x = 0 To cbCount
        If cName = "RunTime" & x Then
           MsgBox("You clicked RunTime" & x & " button")
        End If
      Next
   End If
End Sub


CType is a function which casts the sender object into whatever object you need if possible, in this case a button and we can then reference the name of the clicked button and use standard code to check for each name.

2. The CreateControls button click code

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
   Dim x As Integer
   'create controls for the amount in the textbox
   Try
       For x = 0 To CType(tbButtonAmount.Text, Integer) - 1
           Dim cb As New System.Windows.Forms.Button()
           cb.Size = New System.Drawing.Size(200, 30)
           cb.Location = New System.Drawing.Point(250, 40 + x * 40)
           cb.Name = "RunTime" & CStr(cbCount)
           cb.Text = "RunTime" & CStr(cbCount)
           Me.Controls.Add(cb)
           cbCount += 1
           'add the click event and point to existing click event
           AddHandler cb.Click, AddressOf cbDesignTime_Click
       Next
   Catch
       MsgBox("Please ensure you have entered a number of controls to create in the exbox!")
       tbButtonAmount.Select()
   End Try
End Sub


Again CType is used to convert the amount entered in the textbox to an integer and further on we convert the form level variable cbCount to a string for naming of the buttons.
The key from an event point of view is the AddHandler method. This allows us to dynamically apply the new control to an event handler.
Finally the whole thing is contained in a Try..Catch..End Try block in case no proper number is entered (most likely error), a good example of the new error trapping techniques in vb.net.
Happy Programming.

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Brian O'Connell Microsoft Certified Applications Developer with 10 years experience developing web based applications using asp, asp.net for a Local Authority in Dublin. Clings to a firm belief that a web applicat...

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