<%$, <%@, <%=, <%# ... what's the deal?

Question

I've programmed in both classic ASP and ASP.NET, and I see different tags inside of the markup for server side code.

I've recently come across a good blog on MSDN that goes over the difference between:

<%= (percentage together with equals sign) and
<%# (percent sign and hash/pound/octothorpe)

(<%# is evaluated only at databind, and <%= is evaluated at render), but I also see:

<%$ (percent and dollar sign) and
<%@ (percent sign and at symbol).

I believe <%@ loads things like assemblies and perhaps <%$ loads things from config files? I'm not too sure.

I was just wondering if anyone could clarify all of this for me and possibly explain why it's important to create so many different tags that seemingly have a similar purpose?

Its not hard to google. I had used greater than Percentage equal to in aspx to come on this page...Try it , Bit tricky but works fine ;) — Mayank Pathak, May 18 '15 at 06:53
@RuudLenders, lucky for you and good job Google. In 2014 searching those tags did not return good quality results. — jdbosley, Jun 06 '17 at 20:57

score 310 · Accepted Answer · edited May 09 '13 at 09:47

310

<% %> - is for inline code (especially logic flow)
<%$ %> - is for evaluating expressions (like resource variables)
<%@ %> - is for Page directives, registering assemblies, importing namespaces, etc.
<%= %> - is short-hand for Response.Write (discussed here)
<%# %> - is used for data binding expressions.
<%: %> - is short-hand for Response.Write(Server.HTMLEncode()) ASP.net 4.0+
<%#: %> - is used for data binding expressions and is automatically HTMLEncoded.
<%-- --%> - is for server-side comments

edited May 09 '13 at 09:47

Maris B.

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answered Jun 05 '09 at 18:18

Jose Basilio

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I guess it's because it's an accepted answer, but trying to edit /w the link didn't work. here's the link I tried putting in about the " – John MacIntyre Sep 15 '11 at 21:32
Awesome! I know this is old but I have been looking all over the internet for this info the last 2 days. Thanks! – jdbosley Jul 25 '14 at 16:16
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Is there a name for all these? What are these called as a group? – Vippy Feb 26 '15 at 18:25
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@Vippy They are called *bee stings*. – Ian Boyd Jun 30 '15 at 18:46
@IanBoyd Where does the term *bee stings* come from? – user692942 Mar 15 '16 at 13:27
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@Lankymart Earliest usage i can find is [September 2008](http://stackoverflow.com/a/115212/12597) – Ian Boyd Mar 15 '16 at 19:39
Maybe my testing method sucks, but I can't see a difference between and . Both of them HTML encode the value. – Dan Jameson May 23 '16 at 03:39
@DanJameson Many ASP.Net controls (e.g. TextBox) automatically HTML Encode their contents. If you try outputting a value directly to the page, or even a Label, you'll see the difference between `` and ``. – Benjamin Ray Feb 28 '17 at 14:47
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@Vippy MS calls them [Embedded code blocks](https://msdn.microsoft.com/en-us/library/ms178135.aspx) "Bee stings" is an unofficial term. – shiggity Apr 25 '17 at 14:01

score 5 · Answer 2 · answered Jun 05 '09 at 18:16

5

You've covered 2 of them (<%# is evaluated only at databind, and <%= is evaluated at render), and the answer for "<%@" is that it's compiler directives (ie., stuff like what you'd put on a compiler's command line).

I don't know about "<%$".

answered Jun 05 '09 at 18:16

Michael Burr

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<%$, <%@, <%=, <%# ... what's the deal?

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