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Text Validation Sample 

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This sample compares two ways of validating text:

Security noteSecurity Note

This sample code is provided to illustrate a concept and should not be used in applications or Web sites, as it may not illustrate the safest coding practices. Microsoft assumes no liability for incidental or consequential damages should the sample code be used for purposes other than as intended.

To open the sample file in Solution Explorer

  1. Click Download Sample.

    The File Download message box appears.

  2. Click Open, and on the left column of the zip folder window, click Extract all files.

    The Extraction Wizard opens.

  3. Click Next. You can change the directory that the files will be extracted to, and then click Next again.

  4. Make sure that the Show extracted files check box is selected, and click Finish.

  5. Double-click the sample's .sln file.

    The sample solution is displayed in Solution Explorer. You might get a security warning that says the solution location is not trusted. Click OK to continue.

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.

See Also