Pdf form input validation

Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services. Privacy policy. When users enter data into your application, you may want to verify that the data is valid before your application uses it.

You may require that certain text fields not be zero-length, that a field formatted as a telephone number, or that a string doesn't contain invalid characters. Windows Forms provides several ways for you to validate input in your application. The Desktop Guide documentation for. NET 6 and. NET 5 including. NET Core 3. If you need to require users to enter data in a well-defined format, such as a telephone number or a part number, you can accomplish this quickly and with minimal code by using the MaskedTextBox control.

A mask is a string made up of characters from a masking language that specifies which characters can be entered at any given position in the text box. The control displays a set of prompts to the user. If the user types an incorrect entry, for example, the user types a letter when a digit is required, the control will automatically reject the input.

The masking language that is used by MaskedTextBox is flexible. It allows you to specify required characters, optional characters, literal characters, such as hyphens and parentheses, currency characters, and date separators. The control also works well when bound to a data source. The Format event on a data binding can be used to reformat incoming data to comply with the mask, and the Parse event can be used to reformat outgoing data to comply with the specifications of the data field.

If you want full programmatic control over validation, or need complex validation checks, you should use the validation events that are built into most Windows Forms controls.

Each control that accepts free-form user input has a Validating event that will occur whenever the control requires data validation. In the Validating event-handling method, you can validate user input in several ways. For example, if you have a text box that must contain a postal code, you can do the validation in the following ways:.

If the postal code must belong to a specific group of zip codes, you can do a string comparison on the input to validate the data entered by the user. If the postal code must be in a specific form, you can use regular expressions to validate the data entered by the user. For more information about regular expressions, see. If the postal code must be a valid United States Zip code, you could call a Zip code Web service to validate the data entered by the user.

The Validating event is supplied an object of type CancelEventArgs. A Validate Script can only be entered into other field types with JavaScript. Find out more about the Validate Event from the Articles at the bottom of the page, and from these videos:. Six standard examples for Text Fields. All use Regular Expressions to analyze field data. It would be impossible to provide examples for all the variations on validation. So, the scripts below are categorized into the different parts of validation This kind of validation can be circumvented by the user via specially crafted HTTP requests, so it does not replace server-side input validation.

The validation only occurs when attempting to submit the form, so all restricted inputs must be inside a form in order for validation to occur unless you're using JavaScript. Keep in mind that inputs which are disabled or read-only will not trigger validation. Some newer input types like email , url , tel , date and many more are automatically validated and do not require your own validation constraints.

Use the required attribute to indicate that a field must be completed in order to pass validation. Use the minlength and maxlength attributes to indicate length requirements. Most browsers will prevent the user from typing more than max characters into the box, preventing them from making their entry invalid even before they attempt submission.