Creating custom User Defined Functions (UDFs) is one of the most popular reasons to build an Excel add-in. Add-in Express for Office and .NET supports two methods for building custom UDFs:
- Automation Add-ins (COM)
- XLL add-ins
Each have their pros and cons and this video provides some guidance for when to choose an XLL. And, of course, there is a code demo that is not-to-be-missed!
This video was captured in Visual Studio 2010 with Add-in Express for Microsoft Office and .NET.