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I want to write a basic if statement on my site to display either item 1 or item 2 depending on if a variable is set to true.

I'm not too familiar with .NET and need a little help with the basic structure of how to get an if statement to work on the aspx page

if the purpose is to show or hide a part of the page then you can do the following things

1) wrap it in markup with

<% if(somecondition) { %>
   some html
<% } %>
2) Wrap the parts in a Panel control and in codebehind use the if statement to set the Visible property of the Panel.
                sample code is   <input type="radio" id="Accept" name="optpost" value="1" <% if(item.Accept == 1){  checked="checked" }%>  class="Default" />
– Ihsan chahi
                Sep 18, 2013 at 13:30
                I tried, but it doesn't work. this is my code <% if (false)                                                        { %>                                                     <asp:Label ID="lblQuantity" runat="server" Text='<%# Convert.ToDouble(Eval("Quantity")).ToString("#####0") + " " + Eval("unitMsr") %>'>></asp:Label>                                                     <% } %> but it still show
– John Nguyen
                Feb 10, 2015 at 0:50
                @JohnNguyen Can you create a new question for this and make up the code in a more readable fashion?
– Kris van der Mast
                Feb 10, 2015 at 11:24
                @JohnNguyen It's because your markups is broken, in the end, here:  %>'>></asp:Label> It's one > to much. Hope this hasen't been bothering your for 3 years xD
– Eric Sjöström
                May 30, 2018 at 14:00
Normally you'd just stick the code in Page_Load in your .aspx page's code-behind.
if (someVar) {
    Item1.Visible = true;
    Item2.Visible = false;
} else {
    Item1.Visible = false;
    Item2.Visible = true;
This assumes you've got Item1 and Item2 laid out on the page already.
                I concur with Daniel DiPaolo on how best to handle a toggled ASP.NET page display item based upon a true / false variable.
– JohnH
                May 28, 2015 at 19:59
A complete answer for optional content in the header of a VB.NET aspx page using a master page:
 <%@ Page Language="vb" AutoEventWireup="false" MasterPageFile="~/Site.Master" CodeBehind="some_vb_page.aspx.vb" Inherits="some_vb_page" %> 
 <asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">          
     <% If Request.QueryString("id_query_param") = 123 Then 'Add some VB comment here, 
         'which will not be visible in the rendered source code of the aspx page later %>        
         <!-- add some html content depending on -->
         <!-- the condition in the if statement: -->                
         <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8/jquery.min.js" type="text/javascript" charset="utf-8"></script>
     <% End If %>
</asp:Content>
Where your current page url is something like: 
http://mywebpage.com/some_vb_page.aspx?id_query_param=123
To use C# (C# Script was initialized at 2015)  on ASPX page you can make use the following syntax.
Start Tag:- <%
End tag:- %>
Please make sure that all the C# code must reside inside this <%%> .
Syntax Example:-
<%@ Import Namespace="System.Web.UI.WebControls" %>  (For importing Namespace)
Reference to some basic namespaces for working with ASPX page.
<%@ Import Namespace="System.Web.UI.WebControls" %>
<%@ Import Namespace="System.Diagnostics" %>
<%@ Import Namespace="System" %>
<%@ Import Namespace="System.Web" %>
<%@ Import Namespace="System.Web.UI" %>
<%@ Import Namespace="System.IO" %>
C# Code:-
if (Session["New"] != null)
    Page.Title = ActionController.GetName(Session["New"].ToString());
Features of C# Script:
No need of compilation. Run time execution is occurred like Java Script.
Before using C# script make sure the following things:-
You are on WebForm. Not on WebForm with master page.
If you are in WebForm with master page make sure that you have written your C# script at Master page file.
C# script can be inserted anywhere in the aspx page but after the page meta declaration like
<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="Profile.master.cs" Inherits="OOSDDemo.Profile" %>
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication3.WebForm1" %> (For WebForm)
        
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