How to convert xlsx files into 2003 xls files programatically in C#?

Question

I\'ve found ExcelPackage, a better library than Excel Interop API to create and mantain programatically excel sheets, but they are generated in .xlsx. Most of people that wi

Answer 1

I suspect this won't be a popular answer, but I don't believe that its desirable to convert the files to .xls from .xlsx (I was going to suggest that it wasn't necessary, but, unfortunately, that's a generalisation too far).

The "Microsoft Office Compatibility Pack" is free to download and adds support for the new formats to Office XP and Office 2003 - far better therefore, at least in the general instance, to persuade your users to bring their systems up to spec than to mire yourself in having to deal with office interop (which is basically going to cause you, and quite possibly your users, a lot of pain). Similarly I believe there is support for the new formats in Open Office 3.

I do appreciate that there are circumstances where people will not be allowed to add this capability to their system but for the most part adding the tools as above will make people's lives easier since it will reduce the friction between those using Office 2007 and those using older versions.