thanks for your post.
The fuzzylite library is C++98 (and C++11), so I am afraid it may not compile using C99/11. However, I think it is best to do some research on C projects using C++ libraries or using C++ with C libraries. Any finding, kindly let me know as I am very interested in this. Also, I am available to help and discuss potential approaches to have fuzzylite C++ available for C.