Presently, ASP.NET has six smart validation controls in .NET 3.5.
These controls are called smart valdiation controls because they can perform validation both on client side and server side.
ASP.NET performs browser detection when generating the ASP.NET page and makes decisions based on the information it gleans.
Even if client-side validation is initiated on a page, ASP.NET still performs the server-side validation when it receives the submitted page, thereby ensuring security won’t be compromised.
The available validation server controls are
| Validation Control
|| Checks that the control it has to validate is not empty when the form is submitted.
|| Checks that the value of the associated control is within a
specified range. The value and the range can be numerical, a
date or a string.
|| Checks that the value of the associated control matches a
specified comparison (less than, greater than, and so on)
against another constant value or control.
|| Checks if the value of the control it has to validate matches the specified regular expression.
routine and its server-side counterpart to perform your own
custom validation logic.
|| Shows a summary with the error messages for each failed
validator on the page (or in a pop-up message box).
The BaseValidator Class
The validation control classes are found in the System.Web.UI.WebControls namespace and inherit from the BaseValidator class.
This class defines the basic functionality for a validation control.