Data input validation in Windows Forms is essential.Built-in validation doesn't go much further than an enforcable maximum length for textboxes, but there are some nice methods you can use to make validation a breeze.
The last thing we need is for a Message Box to pop up when we tab away from a field, telling us it's invalid. Also, we don't want all the validation done when the user presses the OK button, because they could then potentially be given a great big message with all the fields that are wrong.In this article, I will walk you through a real world project that I have done that shows how to add your own smart tags to controls. DDMMYYYY End Sub Private Sub Radio Button2_Checked Changed( _ By Val sender As System. You can use the Days In Month() method from the Date class to find out the number of days in a particular month and year. My client specifically wanted an easy way to enter dates without using the mouse to select a date. Is Valid Then Raise Event Validation Failed(Me, New Event Args()) End If End Sub End Class The class also exposes an event called Validation Failed that will be raised if content entered does not match with the pattern indicated by the regular expression. NET regular expression validator provides some built in regular expressions that validate things such as e-mail and zip code. \d-\d" Public Shared SSN As String = "\d-\d-\d" Public Shared ZIP As String = "\d(-\d)?The topic of the next column is yet to be determined.