Therefore, it would help to take a look at the properties and the methods of this base class, which are common for all the validation controls: The Regular Expression Validator allows validating the input text by matching against a pattern of a regular expression.The regular expression is set in the Validation Expression property.
Getting user input through the system requires much attention, and with previous serverside scripting languages, there were no standard way of dealing with form validation.Actually, that's all we need to test the most basic part of the Required Field Validator. Validation is only performed serverside if necessary!I'm sure that all the attributes of the controls makes sense by now, so I won't go into details about them. You should see something like this: If your browser supports Java Script, which most modern browers do, then you will notice that the page is not being posted back to the server - the validation is performed clientside! To see how it feels, you can add enableclientscript="false" to the Required Field Validator and try again.They all work in different ways, but essentially they do the same - they make sure that a form field has been properly filled by the user.The validation control classes are inherited from the Base Validator class hence they inherit its properties and methods.The main advantage is that it prevents a page from being postback to the server until the client validation is executed successfully. Server validation will only performed when Cause Validation is set to true. You can have a Required Field Validator control for each form element on which you wish to enforce Mandatory Field rule.