Visual C# | Advanced LINQ exercise | Shopping days till Xmas using skip/anonymous types

This exercise is provided to allow potential course delegates to choose the correct Wise Owl Microsoft training course, and may not be reproduced in whole or in part in any format without the prior written consent of Wise Owl.

The answer to the exercise will be included and explained if you attend the course listed below!

Software ==> Visual C#  (79 exercises)
Version ==> Any version of C#
Topic ==> Advanced LINQ  (2 exercises)
Level ==> Average difficulty
Course ==> Intermediate C#
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If you haven't already got one, create a Windows Forms project (using Visual C#, obviously) called wiseowl. Right-click on your project in Solution Explorer to add an existing item, and choose the file frmShoppingDays.cs in the above folder.

Make this the default form in Program.cs. When you run your application, you should see a form like this, with the form caption updated:

Shopping days form

When you click on the button, you should see that there are 54 shopping days till Christmas in the form's caption, as here.

 

Imagine now that It's the first of November 2020, and you haven't done ANY Christmas shopping.  Also:

  • you can only bear to shop on a Monday;
  • you know you're doing something next Monday; and
  • you can't bear to shop on the last 2 Mondays before Christmas.

Write a query expression which returns an anonymous type with two properties:

  • PossibleDate - a Monday between "now" and Christmas
  • CountdownDays - the number of days between this date and Christmas.

Your query expression should sort the dates in reverse order, then skip the first two.  Don't forget only to count Mondays.

Now iterate over this (you'll need to reverse it using the Reverse method, and skip the first item) to get this:

Shopping days left

What you should see when you click on the button now.

 

There are no doubt easier ways to do this, but none which teaches LINQ so well!

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