C#

New web site launched

I’ve written a few posts about working with the eBay API, and I’ve been using it a bit as a part-time seller, so I decided to make the tool I wrote available to anyone. The site is called Listing Trends (www.listingtrends.com), and it allows potential sellers to research what is currently hot on eBay. You can drill into individual categories and view the tops results by highest number of watchers, bidders, or the highest price. There are also pages that show listings with a low Buy-It-Now, or listings ......

How to preserve state across pages in a Windows 8 app

When designing a Windows 8 app, you need a way to preserve the state of various items as you navigate from page to page. Windows allows this using the pageState dictionary - a dictionary that can contain any serializable object. If you're a web programmer, you can think of this as similar to using a session variable. Today I'll add this to the cascading ListBoxes shown earlier. You can download the code for that project at ListBoxDrillDown.zip. First, we'll add a navigation button to the page. Put ......

Using cascading ListBoxes to display hierarchical data in Windows 8

When you're dealing with hierarchical data (a tree-like data format such as folders that have sub-folders that have subfolders, etc.) you have to come up with an organized way of displaying it. You could create a tree view, similar to how Windows Explorer displays folders, but I wanted to try something different in Windows 8 - cascading ListBoxes. The user selects an items in a ListBox, and then a new ListBox appears to the right showing the sub-categories. This continues as long as there's data ......

Packt Publishing Thousand Titles Campaign–free eBook!

Packt Publishing is celebrating the release of its 1000th title by offering web site members their choice of free eBook. They are also opening their online library for a week for free to members, to allow you to research your choice. 

If you’re not already a member, signing up is free, but you have to do so by September 30th to get the free eBook.

To sign up, just go to www.packtpub.com/login.

Retrieving a list of eBay categories using the .NET SDK and GetCategoriesCall

eBay offers a .Net SDK for its Trading API - this post will show you the basics of making an API call and retrieving a list of current categories. You'll need the category ID(s) for any apps that post or search eBay. To start, download the latest SDK from https://www.x.com/developer... and create a new console app project. Add a reference to the eBay.Service DLL, and a few using statements: using eBay.Service.Call; using eBay.Service.Core.Sdk; using eBay.Service.Core.Soap; ......

C#–Using a delegate to raise an event from one class to another

Even though this may be a relatively common task for many people, I’ve had to show it to enough new developers that I figured I’d immortalize it… MSDN says “Events enable a class or object to notify other classes or objects when something of interest occurs. The class that sends (or raises) the event is called the publisher and the classes that receive (or handle) the event are called subscribers.” Any time you add a button to a Windows Form or Web app, you can subscribe to the OnClick event, and ......

Dallas event: State of .NET Fall 2011

Don’t miss out on these great session with Markus Egger in the Dallas office! Where: Microsoft Dallas Office – 7000 SR-161 (George Bush Turnpike), Dallas, TX 75039 When: Tuesday, December 13, 2011 – 1:30 – 4:30 PM Signup for this FREE event in Dallas Join Markus Egger, Microsoft RD and one of the longest running MVPs, for an afternoon of free information. CODE Magazine and EPS Software are in a unique position to share information based on real world experience in projects that are either our own ......

Converting calendar date to Julian (Astronomy With Your Personal Computer)

Part 2 of converting the code in Astronomy With Your Personal Computer Astronomers frequently need to do arithmetic with dates, and rather than attempting to count the days in each month, it's far easier to simply convert the dates to Julian day numbers and just add or subtract. A while back I wrote a post on how to do this, but this method is slightly different - the subroutine in the book returns the number of days since 1900 January 0.5 (rather than the actual Julian date) due to the low-precision ......

Converting decimal degrees to degrees/minutes/seconds (Astronomy With Your Personal Computer)

Part 1 of my attempt at converting the code in Astronomy With Your Personal Computer. MINSEC - converting decimal degrees/hours into degrees/hours, minutes, and seconds (and vice-versa). Most astronomy calculations are going to be expressed as degrees, minutes and seconds of arc, but computers need to work in decimal degrees. These methods will allow you to convert from one to the other and back. To convert from decimal to degrees/minutes/seconds: The whole units of degrees will remain the same (i.e. ......

Updating the book Astronomy With Your Personal Computer

Way back in the dark ages (1985 or so) there was a book title Astronomy With Your Personal Computer by Peter Duffett-Smith. This book provided BASIC routines for various astonomical calculations: date/time conversions, planetary location, eclipse information, etc. Some of the calculations would be handy for some mobile apps I'm working on, so I decided to look into converting the code to C#. Just looking at a few lines of the sample programs in the book, it becomes quickly obvious that simply converting ......

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