Exercise: Use the Validating event to check inputs

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Category ==> Visual C Sharp 2010  (65 exercises)
Topic ==> Validating forms  (3 exercises)
Level ==> Average difficulty
Course ==> WinForms using Visual C#
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This exercise asks you to validate form input.  First add the existing form called frmNewHeart from the folder shown above into your project:

Visual C Sharp 2010 exercise - Validating forms (image 1)

Call the ValidateChildren method when you click on the Apply button, but don't do anything else yet at this stage

Now attach code to the Validating event of the txtName textbox, to display a message if it has been left blank:

Visual C Sharp 2010 exercise - Validating forms (image 2)

What your MessageBox could show

Do the same thing for the txtAge field, but for this check also that the age entered is a whole number:

Visual C Sharp 2010 exercise - Validating forms (image 3)

You could use a try / catch clause or the TryParse method to do this

Everyone lies about their age: add code to the txtAge textbox's Validated event to increase the age after it has passed validation:

Visual C Sharp 2010 exercise - Validating forms (image 4)

Make sure you tell the user that you don't trust him/her!

When everything's working OK, close the form down.

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