Validating dates with comparevalidator in 2 0
You need to write the server-based checks anyway for clients without script, so it can be hard to justify writing it all over again for rich clients.
Validation controls change all that, because almost all the duplicated logic is encapsulated in the controls.
The user id must contain 6-10 alpha characters and must not already be in use.
The password must contain 4-12 letters and at least one of the characters "@#$%^&*/." The user must re-enter the password to make sure they entered it correctly.
Let's refine our previous definition a little: "A validator is a control that checks one input control for a specific type of error condition and displays a description of that problem." This is an important definition, because it means that you frequently need to use more than one validator control for each input control.
For example, if you want to check whether or not user input in a text box is (a) nonblank, (b) a valid date between a particular range and (c) less than the date in another text input control, you would want to use three validators.
The final step is to add a validation summary to the top of the page like so: Here is how it looks on the page: Next we need to enforce the character requirements for the User ID and Password fields.
For these we will use Regular Expression Validator controls.
Most Web sites do all of their validation checks on the server.Starting page: The first thing we need to enforce is that the fields get filled in at all.In front of each field, we add a Required Field Validator.DTHML and scripting languages improve things somewhat.It is possible to provide the user with immediate feedback on bad input and to prevent them from posting a page until it has been corrected.
Anthony Moore Microsoft Corporation July 2000 Updated March 2002 Summary: Provides a brief overview of the validation framework in ASP.