question

Question

Custom Controls are derived from which of the classes a) System.Web.UI.Webcontrol b) System.Web.UI.Customcontrol c) System.Web.UI.Customcontrols.Webcontrol tell me the answer

Senthilkumar · Answer

The correct answer is System.Web.UI.WebControls . There is no namespace with the CustomControl or CustomControls.WebControls. The custom controls are nothing but we need to develop our controls on top of the existing ASP.Net web controls. For example we have lot of controls like TextBox Button. If you have a requirement like TextBox should only accept the number then you need to develop your own custom controls. The every control has its own class so the custom control class has to be overriden that properties and events. using System.Web.UI.WebControls namespace MycustomControls { public class TextBoxNumber : TextBox { //Write you logic here to implement custom textbox. } } You can get some example custom control in the following link: http://sumedha7.blogspot.com/2008/07/derived-custom-controls-in-aspnet-20.html

Vulpes · Answer

The answer is (c).

Vulpes · Answer

There is in fact a WebControl class listed in the System.Web.UI.WebControls namespace: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.aspx This is just the base class for other controls in this namespace such as TextBox: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.textbox.aspx In practice of course you'd probably derive your custom control from TextBox Button Label etc rather than directly from WebControl though the latter would still be the ultimate base class of your custom control as well as its parent.

Senthilkumar · Answer

Hi Vulpes I agree that. But if you see the namespace System.Web.UI.WebControls and inside that there is no WebControl class. If you check the TextBox hierarchy shows like System.Web.UI.WebControls.TextBox Can you clarify me on this?

Vulpes · Answer

Actually the correct answer to the question is none of them! When I answered this the first time I knew the first two didn't exist and so thought that it must be the third one. However on checking that today I've discovered that it doesn't exist either! If it were on the list the correct answer would be System.Web.UI.WebControls.WebControl as this is the base class of all web controls in the System.Web.UI.WebControls namespace and hence of all custom controls as well: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.webcontrol.aspx