Exercise: Validate all a form's controls by looping over them

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Category ==> Visual C Sharp 2010  (65 exercises)
Topic ==> Looping  (2 exercises)
Level ==> Average difficulty
Course ==> Introduction to Visual C#
Before you can do this exercise, you'll need to download and unzip this file (if you have any problems doing this, click here for help).

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To avoid having to draw the form needed for this exercise, right-click on the name of your project in Solution Explorer then choose Add --> Existing Item... (you can also press SHIFT + ALT + A to do the same thing).

Choose only the file called frmApplication.cs in the above folder to import it into your project (you may need to overwrite existing files as you do this), then edit Program.cs to make this the default form.  When you run your application, you should now see this:

Application form for dating agency

The button should run code to check all text boxes and combo boxes are filled in.

The problem that you may have is that you can't just loop over all of the controls on a form, because the two group boxes shown will conceal the controls they contain.  Because of this, you'll need the algorithm shown overleaf.

Here's a suggested algorithm (shown in fairly sketchy pseudo-code):

// FOR EACH CONTROL ON THE FORM

 

// IF IT'S A GROUPBOX - IE IF (g is GroupBox)

 

// FOR EACH CONTROL IN THE COLLECTION OF CONTROLS

// WITHIN THIS GROUPBOX g

 

// CHECK THIS CONTROL ISN'T A LABEL (NOT INTERESTED

// IN THESE)

 

// IF THE LENGTH OF THIS CONTROL IS 0, SET THE

// FOCUS TO THIS CONTROL AND REPORT ERROR

When you've checked whether your validation code works OK, close down the application and the form.

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