I have some ExcelDNA C# code which I am working on, and within Excel an xll plugin that I'd like to be able to access. I am not able to get the source code of this plugin - it has to be used as is. So is there a method of being able to access these functions from C#?
Great to see an ExcelDna tag on StackOverflow!
You should take a look at making a call to xlUDF. It should allow you make a call to any UDF (including that of your XLL so long as it's loaded).
The MSDN description is here, with a similar question answered on Google Groups.
I hope this helps - please let me know how you get on as I would like to add xlUDF to my list of ExcelDna examples.
Chris