An AIML interpreter is software that takes a user’s input, selects the “best” match from the collection of AIML files for your bot, then parses the chosen AIML category into a Human readable response. The “chatbot” can be considered to be the collection of AIML files it has, but you need an AIML interpreter (also known as a chatbot engine) to make it work. There are a LOT of different AIML interpreters out there, and selecting the right one for you depends on a lot of factors, such as how the chatbot will be used, what (programming) language the interpreter is written in, your skills and experience in the area, and others. Now we already know that you’re looking for something written in C/C++ for “offline” use, so that narrows the field a lot, but there are still several options to explore. Sadly, this is an area that I have no specific knowledge or experience with, so you’re probably going to need to rely on trial and error, as well as some good, old fashioned research into what will work best for you. I’ll answer any questions that I can, but useful information in this area is going to be hard to come by from me, as I just don’t know all that much about C programming.