how to validate textbox control in c#. ?

hi,

text box has one event called "Validating", with the help of this we can validate the text box.
depending on requirement, we may write common code for validating text box.

please refer below link,
http://blog.scosby.com/post/2010/02/11/Validation-in-Windows-Forms.aspx
http://www.codeproject.com/Articles/13922/Validate-user-input-in-Windows-Forms
http://msdn.microsoft.com/en-IN/library/system.windows.forms.control.validating.aspx

hope this will help you.