Validating after button click

For more information, see the WM_KILLFOCUS topic in the "Keyboard Input Reference" section, and the "Message Deadlocks" section of the "About Messages and Message Queues" topic in the MSDN library at

The following code example uses the derived class Text Box and validates an e-mail address that the user enters.

(Don't worry -- this form doesn't go anywhere.) In my professional opinion as a Java Scripter, it is simply easier to use a flag variable as an indicator of whether or not the form's inputs are valid, and then, if the flag is still valid, to submit the form.

Here's a group of inputs which demonstrate the example.

Then you can display only one validation error in the code itself.

you can use if condition to check first validator got error.

Now practice your newly learned skills on your own and experiment with the error provider control!

Here is just the validating event handler’s code: The event driven validation model in Win Forms is powerful and flexible enough to allow you to create high quality apps that implement robust and maintainable validation code in your forms.Let’s assume when we click our save button that we wish to validate the controls and display an icon if there is a problem.First, add the following code to the Form’s constructor after the Initialize Component method: This is a handy trick to prevent implicit validation of our controls when they lose focus.So we can use an ordinary button instead.) The source for this function, and main focus of this page, I place here: Note the flag is initially set to true.The reason is we will only be checking certain conditions on the form -- and if those conditions pass, then the rest of the form's inputs are assumed valid (otherwise we'd validate them in the function! The first statement checks to see if the line1.value is NOT "Java Script".

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