ASP.NET by Example

RegularExpressionValidator Control

Before we go into this control, let's briefly discuss regular expressions, what they are, and how they are used. A complete coverage of regular expressions is well beyond the scope of this chapter (and this book!), but in this chapter we will provide you with a brief introduction to this powerful tool, along with a number of helpful examples and references to resources where you can find more information. Regular expressions are often the simplest, easiest way to search or compare strings, so they naturally can be very powerful when used to validate user input on forms.

A regular expression is a pattern of text that serves as a template for a particular character pattern. Strings can then be evaluated to determine ...