This is easier for me to understand even though its coded in C#... I will try to code on my own in pure C++... Thanks again =)
It's really not that hard to port (if a C# guy like me was able to do it then it should be easy for a C++ guy), but there's already tons of such code on the web (to decode DigitalProductID's), even in C++, like here. Google will find plenty of relevant hits if you search with terms like DigitalProductID and C++. These kinds of apps have been around for just about forever, so it should be pretty easy to find source code for most major languages.