Validating in asp net
In that case, the validation is performed as users work in the browser.
For example, suppose you specify that a value should be an integer.
The regular expression is set in the Validation Expression property.
The following table summarizes the commonly used syntax constructs for regular expressions: The Custom Validator control allows writing application specific custom validation routines for both the client side and the server side validation.
However, the test will be performed in server code.
Note Even if you use client-side validation, validation is always also performed in server code.
This article discusses how to validate information you get from users — that is, to make sure that users enter valid information in HTML forms in an ASP. What you'll learn: If you ask users to enter information in a page — for example, into a form — it's important to make sure that the values that they enter are valid.
For example, you don't want to process a form that's missing critical information.
It's easy for people to change these values (perhaps for malicious purposes).
So you must check these values in order to protect your application. This test would pass the first time that the page is requested, but not when the request is a form submission.
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If a form is long or complex, reporting errors only after the page is submitted can be inconvenient to the user.