How to register User Control to a Web Form

what is the user control ?

• The extension is .ascx
• can not run as stand-alone files and need to add to a web form
• do not have html, body or form elements

How to Register User Control in a Web Form?

firstly you need to add the user control into your project as a new item .

Then in order to use it ,there are two options to add a user control into a web form.

The first option is :

• Make it accessible to a specific web form if you need the user control only accessible to a specific web form, the user control can register to it by adding below line to the top of your web form :

<%@ Register Src="userControlOne.ascx" TagName="TheTag" TagPrefix="uc1" %>

Src is pointing to user control file name
TagPrefix and TagName is the unique combination to call the user control in a web form content

and then to call the registered user control in web form use below code :

<uc1:TheTag ID="uniqueIdForPartOne" runat="server"></uc1:TheTag>

the second option is :

• Make it accessible to all forms In this case , you need to register it to the Web.config file with below code to the element :

pages>
<controls>
<add tagPrefix="uc1" tagName="TheTagTwo" src="~/controls/userControlTwo.ascx"/>
</controls>
</pages>

In order to resolve the address of user control from the root file , you should use ‘~’ symbol. then you can use the user control from any web form without registering it again, in the same way :

<uc1:TheTagTwo ID="uniqueIdForPartTwo" runat="server"></uc1:TheTagTwo>

download the userControl source from my GitHub.