I have a form where I need to validate the textboxes like Firstname, Middlename, Lastname, emailId, date, mobilenumber. The validation should happen when a user starts typing in the textbox. errorprovider should show message under textbox if a user enters numbers in place of text and text in place of numbers. I got to know about implicit validation and explicit validation but I feel better to use implicit validation only because its on time error provider when user looses focus on text box or if he shifts to another textbox. I've posed this kind of question with a explicit validation code but no one responded me. So Im making it simple to get help. Do not think I havent done enough research before posting this question.
If you have a very specific validation to do, Marc's answer is correct. However, if you only ensure the "enter number instead of letters" or "enter letters instead of numbers" thing, a MaskedTextBox would do the job better than you (user wouldn't be able to answer incorrect data, and you can still warn them by handling the MaskInputRejected event)
http://msdn.microsoft.com/en-us/library/kkx4h3az(v=vs.100).aspx