Validating numeric input reverse dns entries not updating
Place four controls from the Web forms section of the Toolbox onto the form. If Is Valid returns a value of true then all of the validation checks were successful.Drag one Text Box control and give it an ID of First Name Text Box, two Button controls (Submit Button and Cancel Button), and one Required Field Validator (First Name Required Field Validator). The following screen shows the form in action, and the user has pressed the Submit button without entering any text into the textbox. The Required Field Validator fails when the value in the associated control matches the value of the Initial Value property of the Required Field Validator.
As we will see later in the code-behind file, the Cancel Button will clear all of the fields on the form, and we do not want to validate any of the fields when the user presses this button. If any one of the validation controls on a form fails, the script cancels the postback operation and displays error messages on the form.(Which actually isn't very common.)First, some code to test the validation. (I have a more complete tutorial on Reg Ex here: Regular Expressions in VB.I created a quick form with a Text Box, a Button, and two labels occupying the same location to report the answer by making one or the other visible. Click If -- Test for numeric characters -- lbl Not Int. Visible = True End Sub Private Sub Test String In_Text Changed( By Val sender As System. For instance, if your application expects users to type a number, but they type something that can't be interpreted as a number, your code could crash.Use the Is Numeric() function to determine whether a value can be safely converted into a number.