required field validator in windows form

Question

How to provide required field validator in windows form application c# and how to use Error Provider

Santhosh Kumar Jayaraman · Answer

Validation is already built into the WinForms library. Each Control -derived object has two events named Validating and Validated . Also it has a property called CausesValidation When this is set to true (it is true by default) then the control participates in validation. Otherwise it does not. Validation occurs as part of focus. When you focus off of a control its validation events are fired. In fact the focus events are fired in a specific order. When you change the focus by using the keyboard (TAB SHIFT+TAB and so on) by calling the Select or SelectNextControl methods or by setting the ContainerControl..::.ActiveControl property to the current form focus events occur in the following order: Enter GotFocus Leave Validating Validated LostFocus When you change the focus by using the mouse or by calling the Focus method focus events occur in the following order: Enter GotFocus LostFocus Leave Validating Validated If the CausesValidation property is set to false the Validating and Validated events are suppressed. If the Cancel property of the CancelEventArgs is set to true in the Validating event delegate all events that would usually occur after the Validating event are suppressed. Check this. http://msdn.microsoft.com/en-us/library/ms950965.aspx