excel add in to save internal data?

Question

I am new to writing excel add-in (in C#) and trying to figure out the right way to save some internal data structures so I can restore the state the next time file is opened. I can convert data in xml or base64 strings if it makes things easier. I don't want to maintain a separate file and would like to embed this information inside excel worksheet.

Many thanks for your help.

Answer 1

Use a cell in an invisible sheet (you can name it, for example, "internal data sheet") for storing the information. Excel sheets have a Visible property which can be set programmatically to `xlVeryHidden' which means it can only be made visible again by a program. Here you find some more information:

http://support.microsoft.com/kb/142530/en-us