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?

Answer 1

• <% %> – 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