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Text Validation Sample

Visual Studio 2008

This sample compares two ways of validating text:

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Security noteSecurity Note:

This sample code is intended to illustrate a concept, and it shows only the code that is relevant to that concept. It may not meet the security requirements for a specific environment, and it should not be used exactly as shown. We recommend that you add security and error-handling code to make your projects more secure and robust. Microsoft provides this sample code "AS IS" with no warranties.

To run this sample

  • Press F5.

This sample shows how you can create a set of special-purpose text boxes that are designed for a specific type of input. This sample includes text boxes for e-mail addresses, IP addresses, and phone numbers.

The MaskedTextBox control provides validation as the user types, so incorrect text never appears in the MaskedTextBox.

The RegExTextBox class, derived from TextBox in this sample, serves at the base class for several other controls. This class validates the contents of the TextBox control against a given regular expression. When the user clicks the Validate button on the main form, the code loops through the controls collection to find all the RegExTextBox controls, then casts them to that base type to call the IsValid property. If the input is invalid, the TextBox text color will be red.