Excel Library XLL File - Where to start?

[MattGreer]

I downloaded a file that allows a function to calculate the molecular weight of a given compound using the formula =MW("CH4") (for example). The file I downloaded is a XLL file, which I understand is an Excel Library.

I know nothing of these files but do know quite a bit about VBA and VBS. Where do I start learning about these files? Is there a way to open this file and take a look at what's going on inside it? How do I do this?


Thanks!!


Matt

 

[PHV]

XLL files are DLL designed and compiled for Excel.
So you can't take a look inside it.

Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ222-2244

 

[XLDennis]

Hi,

Unlike Excel's usual add-in it's compiled files created usually with C/C++.

For a start to read about it check out the following article in MS Knowledge Base:

http://support.microsoft.com/default.aspx?scid=kb;en-us;Q178474

You will also need Excel's SDK which have been out of print for the last years so check with Amazon to get a copy of:

Microsoft Excel 97 Developer's kit
Baarns Consulting Group Inc
Microsoft Press 1-57231-498-2 1997

Nowadays I recommend to use legacy 6.0 and develop add-ins as ActiveX-DLLs.

Here is an article from MS Knowledge Base:

http://support.microsoft.com/default.aspx?scid=kb;en-us;Q285337

There are two good reason for using XLL/DLL instead of standard add-ins (xla):
1) VBa is an interpretating language while DLLs are compiled.
2) They are much more secured and protect the code very well.

Kind regards,
Dennis





Simple code and a simple life.

 

[MattGreer]

Thanks to both of you for the information.

Would you all recommend using the XLL type arrangement to create a similar add-in for Excel?

Something of this sort would be an excellent starter project for me as it's not so complicated calculation-wise, so I'll be able to focus on the code.

Is there any way to protect yourself from malicious XLL files? How can you trust that someone didn't put something inappropriate in there?

Thanks!!


Matt

 

[XLDennis]

Hi Matt,

In general I always encourage people to explore things that they find is interesting.

Before I forget it again:
Creating COM add-ins in VB 6.0 that include functions can only be done for Excel 2002 and later (at least in an easy way) while XLL are applicable to all versions.

Yes, setup a small and simpel project and test it out. Then You can expand it. One important aspect is that the XLLs need to be registrated on the computer before they can be used and therefore You will need to explore this aspect as well.

Nowadays we can't be sure of anything.. Perhaps the risk is little but as long as there are possibilities we can't be 100 % sure of anything.

Anyway, good luck and let me know how things progress for You

Kind regards,
Dennis

Simple code and a simple life.