Read original post at Jerry Nixon's Blog
Whoa! I am getting a lot of questions on data validation. This warrants an article. Of course, we have many choices. Some are prescriptive, some are simple, and some are just not reliable.
For now, I will just limit data entry to valid numbers. That doesn’t mean Char.IsNumeric. Commas and periods are valid. I also have to remember valid keys like shift, backspace, and tab.