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RegularExpressionValidator.ValidationExpression Property

Gets or sets the regular expression assigned to be the validation criteria. The default value is an empty string (""). This API is obsolete. For information about how to develop ASP.NET mobile applications, see the Web site.

Namespace:  System.Web.UI.MobileControls
Assembly:  System.Web.Mobile (in System.Web.Mobile.dll)

public string ValidationExpression { get; set; }
<asp:RegularExpressionValidator ValidationExpression="String" />

Property Value

Type: System.String
The regular expression assigned to be the validation criteria.
The RegularExpressionValidator does not perform validation on an empty string. To test for an empty string, use the RequiredFieldValidator and RegularExpressionValidator controls together.


The regular expression assigned was malformed.

The following table shows some sample validation expressions:

Type of Validation

Validation Expression



Phone number

((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4}



.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.