October 2003
Intermediate to advanced
736 pages
15h 25m
English
Content preview from Windows Forms Programming in Visual Basic .NETBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Data Validation
You should never trust your users. We don't mean you can't trust them to pay (a separate issue that we won't go into here). We mean you can't trust the data that your users enter. They may not give you all the data that you need, or they may not give you data in the correct format. List boxes, radio buttons, and all the other controls that give users choices do so to make sure that they provide data in the correct format. However, sometimes you need to validate free-form data entry, such as what a user types into a text box. For that, you handle a control's Validating event:
Sub applicantNameTextBox_Validating(object As Sender, _ e As CancelEventArgs) _ Handles applicantNameTextBox.Validating ' Check for existence of application ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.