How to exchage data with other programs?

[Jürgen Ritzau]

Hello,

using Excel 2000 VBA, I want to call a self-made C-program.
This program should get a value from the VBA Macro, than make
some calculations an the result I want to have back in the VBA
macro.

How I can achieve this? Is this possible using a Win32 command line
C-program or do I need a Win32 GUI application for my problem?

I need some basic hints about how to exchange data using Excel and
other programs (which are _not_ Word, Access, ..., it will be
self made).

Many thaks for any hint!

Juergen