ASP.NET RegularExpressionValidator Control
This validator is used to validate the value of an input control against the pattern defined by a regular expression.
It allows us to check and validate predictable sequences of characters like: e-mail address, telephone number etc.
The ValidationExpression property is used to specify the regular expression, this expression is used to validate input control.
Here, in the following example, we are explaining how to use RegularExpressionValidator control to validate the user input against the given pattern.
It produces the following output when view in the browser.
It will validate email format as we specified in regular expression. If validation fails, it throws an error message.