Content

ASP.NET Inline Directives
<% ⋯ %> Embedded Code Block
<%= ⋯ %> Displaying Expression
<%@ ⋯ %> Directive Expression
<%# ⋯ %> Data-binding Expression
<%$ ⋯ %> Expression Builder
<%-- ⋯ %> Server-side Comments Block
<%: ⋯ %> HTML Encoded Data-Binding Expression
Source/Reference

ASP.NET Inline Directives

The supported ASP.NET inline directives for ASP.NET scripting are <% ⋯ %>, <%= ⋯ %>, <%@ ⋯ %>, <%# ⋯ %>, <%$ ⋯ %>, <%-- ⋯ %>, and <%: ⋯ %>.

<% ⋯ %> Embedded Code Block

The <% ⋯ %> embedded code block is used to preserve backward compatibility with classical ASP. The code in the block can execute programming statements and call functions in the current page class during the page-rendering phase.

<%= ⋯ %> Displaying Expression

The <%= ⋯ %> displaying expression is an equivalent of the embedded code block that contains only the Response.Write(⋯) statement. This is the simplest way to display information such as a single string, an int variable, or a constant.

The displaying expression cannot be used in the attributes of server controls. This is because the .NET Framework directly compiles the whole expression instead of the displaying content as the value to the attribute.

<%@ ⋯ %> Directive Expression

The <%@ ⋯ %> directive expression is the syntax that specifies settings that are used by the page, by user control, and by application compilers when they process ASP.NET Web Form (.aspx) pages, User Control (.ascx) files, and Global (.asax) files.

<%# ⋯ %> Data-binding Expression

The <%# ⋯ %> data-binding expression creates binding between a server control property and a data source when the control’s DataBind method of this server control is called on the page.

<%$ ⋯ %> Expression Builder

The <%$ ⋯ %> expression builder is used to set values of control properties based on the information that is contained in an application's configuration or resource files. The following is the basic syntax of the expression builder:

<%$ Expression Prefix: Expression Value %>

The dollar sign ($) indicates to ASP.NET that the following expression is an expression builder. The expression prefix defines the kind of expression, such as AppSettings, ConnectionStrings, or Resources. Additionally, you can create and define your own expression builder. The expression value that follows the colon (:) is what ASP.NET will actually use as the value of a certain property.

<%-- ⋯ %> Server-side Comments Block

The <%-- ⋯ %> server-side comments block lets developers embed code comments in any location of the HTML source of ASP.NET Web Form pages (except for within <script> code blocks). Any content between the opening and closing tags of the server-side comments block will not be processed on the server or rendered on the resulting page.

<%: ⋯ %> HTML Encoded Data-Binding Expression

The <%: ⋯ %> HTML Encoded Data-Binding Expression is used to HTML-encode the result of data-binding expressions. Add a colon (:) to the end of the <%# prefix that marks the data-binding expression.

Source/Reference

https://support.microsoft.com/en-us/help/976112/introduction-to-asp-net-inline-expressions-in-the-net-framework
https://docs.microsoft.com/en-us/aspnet/whitepapers/whats-new-in-aspnet-45-and-visual-studio-2012#_Toc318097391
https://weblogs.asp.net/scottgu/new-lt-gt-syntax-for-html-encoding-output-in-asp-net-4-and-asp-net-mvc-2

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ID: 190700004 Last Updated: 7/4/2019 Revision: 0 Ref:

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