Unicode strings and XLLs

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Unicode strings and XLLs
UDF function for Excel, using XLLAddin returns ??? for è??Ã? 
Claudiu Toma




Posts: 42
 Joined: 2007-09-04
Issue:

I have an XLL add-in (XLLAddin project created w/ addin express version:
Add-in Express?Â?Ô?? 2007 for .NET v3.8.1886).
with a function that returns a string like for instance:
è??Ã?ê (in case you cannot see these chars type ALT-0232 ALT-0193 ALT-0194 ALT-0195 ALT-0218 ALT-0234 in Excel).

Office 2003 doesn't display these chars correctly in the cell. It displays "?" question marks instead.

1. I can insert these chars in Excel 2003 just fine from my Excel COM Add-In by setting the current cell's Value and the chars displays OK, however if this same string comes from the XLL add-in formula it will show "?" instead.
The reason for this seems to be Excel converting the string from Unicode encoding C# to ASCII enconding, loosing all these characters in the process therefore showing "?" instead.
I read this post here:
http://msdn2.microsoft.com/en-us/library/aa730920.aspx
Strings
For the first time, Excel 2007 gives XLLs direct access to wide character Unicode...



2. Can we return an array of bytes instead of a string (C#) in the XLL, so that the C# UDF function to have a return value of type byte[] instead of string? It looks like it's not supported? so that in my C# UDF instead of returning 
...
return sRet; //where sret has those è??Ã?ê chars


I would do something like: 

byte[] myTranslation = Encoding.Default.GetBytes(sRet);


or 

byte[] myTranslation = Encoding.ASCII.GetBytes(sRet);


returning an array of bytes instead of a string to try a workaround that Office's encoding conversion issue in the formula.

2. Doing an automation add-in might help since the limitation is not there, but automation add-ins are only supported starting with Office XP (2002), and we need to support Office 2000.

3. I know of a previous post on a similar case but I didn't see a resolution on the issue:
http://www.add-in-express.com/forum/read.php?FID=5&TID=2796&MID=13214&phrase_id=733771#message13214

Any suggestions?

Your insight is greatly appreciated on the issue since supporting
Office 2000 is critical to this project.

Thanks,

Posted 25 Feb, 2008 19:36:21 Top
Claudiu Toma




Posts: 42
 Joined: 2007-09-04
Forgot to mention that it works fine in Office 2007.
Posted 25 Feb, 2008 19:55:24 Top
Sergey Grischenko


Add-in Express team


Posts: 7233
 Joined: 2004-07-05
Hi Claudiu.

I am afraid I can't say more than I described in the topic above.
Posted 26 Feb, 2008 08:35:10 Top