When should I use # and = in ASP.NET controls?

Question

I have been using ASP.NET for years, but I can never remember when using the # and = are appropriate.

For example:

<%= Grid.ClientID %> 

or

<%# Eval("FullName")%> 

Can someone explain when each should be used so I can keep it straight in my mind? Is # only used in controls that support databinding?

Answer 1

There are a couple of different 'bee-stings':

• <%@ - page directive
• <%$ - resource access
• <%= - explicit output to page
• <%# - data binding
• <%-- - server side comment block

Also new in ASP.Net 4:

• <%: - writes out to the page, but with HTML encoded

Also new in ASP.Net 4.5:

• <%#: - HTML encoded data binding