Question

This is the Design:::

<asp:Panel ID="Panel1" runat="server">
</asp:Panel>
<asp:Button ID="Button2" runat="server" Text="Button" />
<asp:Label ID="l1" runat="server" Text="0"></asp:Label>
<asp:Label ID="l2" runat="server" Text="0"></asp:Label>



Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
    Dim i As Integer = 0
    Dim j As Integer = 0
    l1.Text = l2.Text
    l2.Text = Val(l2.Text) + 10
    i = Val(l1.Text)
    j = Val(l2.Text)
    MsgBox(i & " " & j)
    While (i < j)
        Dim b As Button = New Button()
        b.ID = "b" + i.ToString()
        b.Text = b.ID
        Panel1.Controls.Add(b)
        i = i + 1
    End While
End Sub

This contains a button on click it should create 10 unique buttons..
i want to append all created buttons with existing buttons..
but the program is overriding instead of adding controls to the panel
help me.

Answer 1

I think you want to add 10 dynamic controls on every button click. The problem you are facing right know is that on first click it adds 10 button controls, and on subsequent clicks it overrides the previous controls. Dynamic controls are created every time the page is requested so you have to create them on every request.

I write the following code to solve your query and it works:

// Aspx code
<asp:Panel ID="Panel1" runat="server">
 </asp:Panel>
<asp:Button ID="Button2" runat="server" Text="Button" />
<asp:Label ID="l1" runat="server" Text="0"></asp:Label>
<asp:Label ID="l2" runat="server" Text="0"></asp:Label>

// Code BEhind

 Protected Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    Dim i As Integer = 0
    Dim j As Integer = 0
    l1.Text = l2.Text
    l2.Text = Val(l2.Text) + 10
    i = Val(l1.Text)
    j = Val(l2.Text)
    MsgBox(i & " " & j)

    Dim lst As List(Of Integer) = New List(Of Integer)  'Create a list of integer type
    lst.Add(i)  'Save value of i
    lst.Add(j)

    If Not Session("id_0") Is Nothing Then ' Will Check session for First Click exist or not

        For k As Integer = 0 To DirectCast(Session("click"), Integer)

            Dim mylst As List(Of Integer) = New List(Of Integer)
            mylst = DirectCast(Session("id_" & k), List(Of Integer)) ' Assign Session Value to List
            If Not mylst Is Nothing Then
                WriteControls(mylst(0), mylst(1)) ' Call the function
            End If


        Next


    End If

    Session("id_" & DirectCast(Session("click"), Integer)) = lst  ' Saves the entire list in Session

    WriteControls(i, j)  ' Function Call

End Sub

Private Sub WriteControls(i As Integer, j As Integer)  ' Function to write button control
    While (i < j)
        Dim b As Button = New Button()
        b.ID = "b" + i.ToString()
        b.Text = b.ID
        b.ViewStateMode = UI.ViewStateMode.Enabled
        Panel1.Controls.Add(b)
        i = i + 1
    End While
    Session("click") = DirectCast(Session("click"), Integer) + 1
End Sub

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then          
        Session("click") = 0   ' Stores the no. of Clicks of the button
    End If

End Sub

' Output
' If I press three times button then there will be 30 buttons
b0 b1 b2 b3 b4 ............................................... b29
20 30