Define and use control : Define Control « User Control and Master Page « ASP.Net

Define and use control
<%@ Register 
    TagPrefix="My" 
    TagName="ZipCodeLookUp" 
    Src=".\ZipCodeLookUp.ascx" 
%>
<script runat=server>
Sub SubmitBtn_Click(Sender As Object, E As EventArgs)
    lblMessage.Text = "You selected " _
        & ZipCode1.City & ", " _
        & ZipCode1.State & " " _
        & ZipCode1.ZipCode
End Sub
</script>
<html>
<BODY>
<form runat="server">
<Font Face="Tahoma">
<My:ZipCodeLookUp 
    id="ZipCode1" 
    runat="server"
/>
<BR>
<asp:Label
    id="lblMessage"
    runat="server"
    Font-Bold="True"
/>
<BR><BR>
<asp:button 
    id="butOK"
    text="OK"
    Type="Submit"
    OnClick="SubmitBtn_Click" 
    runat="server"
/>
</Font>
</form>
</body>
</html>


<%-- ZipCodeLookUp.ascx

<script language="VB" runat="server">
Sub Page_Load(ByVal Sender as Object, ByVal E as EventArgs)
    If Not IsPostBack Then
        lblCity.Text = "Albuquerque"
        lblState.Text = "New Mexico"
    End If
End Sub
Sub ZipCodeChanged(sender As Object, e As EventArgs)        
    If ddlZipCode.SelectedItem.Value = "87112" Then
        lblCity.Text = "Albuquerque"
        lblState.Text = "New Mexico"
    ElseIf ddlZipCode.SelectedItem.Value = "08520" Then
        lblCity.Text = "Hightstown"
        lblState.Text = "New Jersey"
    Else
        lblCity.Text = "Indianapolis"
        lblState.Text = "Indiana"
    End If    
End Sub
Public ReadOnly Property City() As String
    Get
        City = lblCity.Text
    End Get
End Property
Public ReadOnly Property State() As String
    Get
        State = lblState.Text
    End Get
End Property
Public ReadOnly Property ZipCode() As String
    Get
        ZipCode = ddlZipCode.SelectedItem.Text
    End Get
End Property
</script>
<Table style="font: 10pt verdana;border-width:1;border-style:solid;border-color:black;" cellspacing="15">
<TR>
<TD><B>Select Zip Code: </B></TD>
<TD>
<ASP:DropDownList 
    id="ddlZipCode"
    runat=server
    AutoPostBack=True
    OnSelectedIndexChanged="ZipCodeChanged"
>
    <asp:ListItem Value="87112" Selected="True">87112</asp:ListItem>
    <asp:ListItem Value="08520">08520</asp:ListItem>
    <asp:ListItem Value="46311">46311</asp:ListItem>
</ASP:DropDownList>
</TD>
</TR>
<TR>
<TD><B>City: </B></TD>
<TD>
<ASP:Label 
    id="lblCity" 
    runat="server"
/>
</TD>
</TR>
<TR>
<TD><B>State: </B></TD>
<TD>
<ASP:Label 
    id="lblState" 
    runat="server"
/>
</TD>
</TR>
</Table>

--%>
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