Let's give it a try, and add a Required Field Validator to our page.We will also add a Text Box to validate, as well as a button to submit the form with.There are 2 code paths for validation failure, and in each case we provide the user with an appropriate error message.
You can use it to make sure that the user has entered something in a Text Box control. Run(form1) End Sub End Class Public Class Form1 Inherits System. Protected Overloads Overrides Sub Dispose(By Val disposing As Boolean) If disposing Then If Not (components Is Nothing) Then components. Dispose(disposing) End Sub 'Required by the Windows Form Designer Private components As System. IContainer 'NOTE: The following procedure is required by the Windows Form Designer 'It can be modified using the Windows Form Designer. Forms Public Class Main Class Shared Sub Main() Dim form1 As Form = New Form1 Application. Initialize Component() 'Add any initialization after the Initialize Component() call End Sub 'Form overrides dispose to clean up the component list. Sample problem: set parameter by entering value into a Text Box, check if value is a number in given range, allow clicking a Button if validation was successful. In this example a derived class Double Range Rule will check if user entered a number (double) within a given range (between Max and Min value).
Controls that helps creating custom validation rules for user input.Let’s assume when we click our save button that we wish to validate the controls and display an icon if there is a problem.