This is a complete system to construct NFA, DFA and minimum DFA from a given regular expression on the alphabet [a-z] and simulate the DFA on any possible input.

It is only support operations of *(closure), .(connection), and |(or), which means if u want to input "abb[a-c]", please input "abb(a|b|c)", this feature may be implemented in the future (if I have time).

I credit this as a significant basis for my work, regex to NFA of my project is based on this C++ implementation.