Custom textbox validating user input in
Typically you will be validating text that is provided by a Text Box, but it could also come from a Combo Box where the user can type their selection.As for validating the text, it can range from simply ensuring there is value (i.e., not an empty string) or more complex task such as validating the format of an email address. Once you have written a validation function for a specific format, convert it into a snippet, so the next time you need to validate similar data, you will save time by simply inserting your snippet.It displays an icon next to the control indicating an error as well as displaying an error message when the user hovers the mouse over the icon.For more details on the Error Provider control, refer to the Spotlight on the Error Provider article.This is done by passing property in the Validating event (because users may not like it when they cannot select another field when the validation fails), then it is recommended to remove the Validated event and update the Validating event as follows: For more complex validation, such as validating an email address, you may need to rely on Regular Expressions.Regular expressions are useful because it allows you to match complex data by providing formatting information.There is no need to validate a control that loses focus when the user wishes to cancel out of the form; therefore, the button’s Causes Validation property can be set to false.As it turns out, validating controls depends on what type of control and the format of the data you wish to validate.
Example use of a regular expression in Power Shell: In this example we are matching any string that contains the word “shell”.
By using Parameter validation you can as validate Text Box values as well; although this isn’t necessary the best method.