Rapid Application Development / Advanced Excel Development

Visual Studio Excel Xll Base Project

Whilst the xll features of Excel offer excellent functionality and superb performance, they are not for the faint hearted. Excel/VBA developers especially have trouble deciphering the documentation. Add in the need to use a different development environment and language and its easy to see why this powerful option is often rejected.

Download the zip here.

Xll Series Contents

(note this is a work in progress - more pages will be added and linked too as and when we have time to complete them to an acceptable level)

• Series intro
• Brief introduction to xlls - what, why, etc.
• The Codematic xll base project (this page)
• Installing Visual Studio C++ 2008 Express.
• Installing the Excel Xll SDK for use with Visual Studio 2008 (C++ Express)
• Very brief overview of C and C++ editors (VS2008)
• Creating a simple dll
• Debugging xlls
• Introduction to XLM.
• Using CALL to access external dll functions from XLM
• Registering dll functions for use from a worksheet cell - using XLM and VBA
• The XLOPER data type and xlcall.h
• The Excel4() function and xlcall.h
• Converting a dll to xll by adding in the registration information
• The Microsoft xll Software Development Kit and framework.
• The Codematic custom xll development service

Codematic Base Xll project

This project is designed to be as easy as possible to use as an introduction to creating xlls.

Even opening it is as easy as possible:
There is a .dsw for Visual C++6.0 users and a .sln for (the free) Visual Studio C++ Express 2008. If you are using a version of Visual Studio between these open the .dsw and accept the offer to convert it to your VS version.

Creating an xll requires a whole bunch of scaffolding, which you can completely ignore once its in place. We have tried to put it in place for you so you don't ever have to consider it.

Part of that scaffolding is the Excel xll SDK from Microsoft. There are two versions of this. The Excel 97 version and the Excel 2007 version.
The Excel 97 version doesn't work so well with modern compilers. The 2007 one is quite a bit more complex to cope with the additional features of 2007.

The Codematic solution was to modify the single function that causes issues in modern compilers and stick with the 97 version, simply because that is more straightforward to understand for less experienced C/C++ devs.

The Microsoft SDK files are the ones highlighted here:

This base project is not meant for extremely complex systems, more for fairly simple lightweight functions, with the emphasis on easy to follow with limited C/C++ knowledge.

Whilst it may appear complex at first, many of the components can be basically ignored.

Here is a brief summary of each file from the included readme.txt:

Headers:
RegFuncs.h - (DO NOT EDIT) holds the prototypes for the registration and unregistration functions
TheAddin.h - (DO NOT EDIT) holds the definition of EXPORT
xlHelpers.h - (DO NOT EDIT) holds a few includes in a way that make them easier to manage.
TheFuncs.h - (DO NOT EDIT) Holds a couple of includes and the prototypes for the functions of the add-in. Add prototypes for new functions in here

TheAddin.def - (DO NOT EDIT) holds the export specification so C++ does not mangle the names so badly Excel cannot read it. Add new function names in the bottom section

Source files:
fw.c - (DO NOT EDIT) holds an include for the Microsoft xll SDK source code framewrk.c
TheAddin.c - (DO NOT EDIT) holds some includes and the open close control routines. May want to edit/remove the open/close messages
RegFuncs.c - (DO NOT EDIT) holds the actual registration and unregistration functions that are called on open/close
TheFuncs.c - this is where the actual function bodies can be added/edited. Note any parameter changes may need to reflected in the registration function.

If you used the Codematic xll generator to specify the function details you should only need to edit TheFuncs.c, everything else is autogenerated. You can use the generator to round trip the code if you later want to add more functions etc. Or you can go in a manually edit the following files:
TheFuncs.h (add function prototypes)
TheAddin.def (add exported name that will be visible from Excel sheets)
RegFuncs.c (add registration and unregistration blocks)
TheFuncs.c (add function bodies here)

Base project

Here is a base xll project (in C) to get you started. It contains a single UDF that takes two arguments and returns the total. It is in Visual Studio 6 format which every version since can open and translate fine. You do need a C/C++ version of Visual Studio though, like for example the free Visual C++ Express 2008.

If you require any more information please get in touch.