ASP. NET-how to: Verify ASP. NET Server controls by Mode

You can check whether user input matches the predefined mode, such as phone number, zip code, and email address. To perform this verification, you must use a regular expression.

1. Add the regularexpressionvalidator control to the page and set the following attributes:

Attribute	Description
Controltovalidate	The ID of the control being verified.
Errormessage, text, display	These attributes specify the text and location of errors to be displayed when verification fails.

 

2. Set the validationexpression attribute to a regular expression to set the mode to be compared.

To allow multiple valid modes, use the bar character (|) to separate expressions.

Note: In client verification, ecmascript (JavaScript) is used to calculate the regular expression. This is slightly different from the regular expression check on the server.

 

3. Add a test in ASP. NET webpage code to check the validity.

The following code example shows how to use the regularexpressionvalidator control to check whether a user has entered a valid U.S. zip code. The validators check two modes: a 5-digit number and a 5-digit number plus four additional digits.

ZIP: <asp: textbox id = "txtzip" runat = "server"> </ASP: textbox>

<Asp: regularexpressionvalidator

Id = "txtzip_validation" runat = "server"

Controltovalidate = "txtzip"

Errormessage = "enter a valid us zip code ."

Validationexpression = "/d {5} (-/d {4 })? ">

</ASP: regularexpressionvalidator>