For example, you can specify that users must fill in a Name text box before they can submit a registration form.
If validation is being performed on the client, the user can leave a required field blank (or with its default value) while working in the page, but must provide a non-default value before submitting the page.
The server side validation routine should be written in any . The summary displays the values of the Error Message property of all validation controls that failed validation.
The following two mutually inclusive properties list out the error message: Complex pages have different groups of information provided in different panels.
To create a validation group, you should put the input controls and the validation controls into the same logical group by setting their Validation Group property.
This type of validation enables you to check for predictable sequences of characters, such as those in e-mail addresses, telephone numbers, postal codes, and so on.
The best way to confirm an email address is to email the user, and get the user to reply by clicking on a link to validate that they have recieved the email (the way most sign-up systems work). You should prevent XSS exploits, SQL injection and so on by escaping correctly when inserting strings into a different language where some characters are "magic", eg, when inserting strings in HTML or SQL.
The regex to confirm the syntax is correct can be very long (see example).
The client side validation routine should be written in a scripting language, such as Java Script or VBScript, which the browser can understand.
The server side validation routine must be called from the control's Server Validate event handler. The basic syntax for the control is as given: The Validation Summary control does not perform any validation but shows a summary of all errors in the page.