Inline ASP.Net Tags, Code Render Blocks... (<%$, <%=, <%, <%#, etc.)

5. November 2011 Niranjan Singh ASP.NET Comments (0)

Code render blocks define inline code or inline expressions that execute when the page is rendered. There are two styles of code render blocks: inline code and inline expressions.
Use inline expressions as a shortcut for calling the Write method.

<% inline code %>
<%=inline expression %>

thee tags are evaluated during the Render portion of the page load cycle.

<% ... %>

The most basic inline tag, basically runs normal code:

<% if (User.IsInRole("admin")) { %> 
  You can see this 
<% } else { %> 
  You are no admin fool! 
<%} %>

http://msdn2.microsoft.com/en-us/library/ms178135(vs.80).aspx

 

<%= ... %>

Used for small chunks of information, usually from objects and single pieces of information like a single string or int variable:

The Date is now <%= DateTime.Now.ToShortDateString() %>
The value of string1 is <%= string1 %>

http://msdn2.microsoft.com/en-us/library/6dwsdcf5(VS.71).aspx

*note: <%= is the equivalent of Response.Write() .

 

<%# .. %>

Used for Binding Expressions; such as Eval and Bind, most often found in data controls like GridView, Repeater, etc.: 

<asp:Repeater ID="rptMeetings" DataSourceID="meetings" runat="server"> 
    <ItemTemplate> 
        <%# Eval("MeetingName") %> 
    </ItemTemplate> 
</asp:Repeater>

 

http://msdn2.microsoft.com/en-us/library/ms178366.aspx

 

<%$ ... %>

Used for expressions, not code; often seen with DataSources:

<asp:SqlDataSource ID="party" runat="server" ConnectionString="<%$ ConnectionStrings:letsParty %>" SelectCommand="SELECT * FROM [table]" />

http://msdn2.microsoft.com/en-us/library/d5bd1tad.aspx

 

<%@ ... %>

This is for directive syntax; basically the stuff you see at the top your your aspx pages like control registration and page declaration:

<%@ Page Language="C#" MasterPageFile="~/MasterPage.master"
AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" Title="Untitled Page" %> 
<%@ Register TagPrefix="wp" Namespace="CustomWebParts" %>

http://msdn2.microsoft.com/en-us/library/xz702w3e(VS.80).aspx

 

<%-- ... --%>

This is a server side comment, stuff you don't want anyone without code access to see:

    <asp:Label ID="lblAwesome" runat="server" /> 
    <%-- sometimes end users make me angry --%> 
    <asp:LinkButton ID="lbEdit" Text="Edit" OnClick="Edit_Click" runat="server" />

http://msdn2.microsoft.com/en-us/library/4acf8afk.aspx

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