NFA to DFA in C programming Language


All job seekers look for the perfect job to give direction to their career. And similarly, the firms hire the candidates applying for a job by their knowledge, ability and other skills. They take tests, interviews and many other processes are there through which the candidate has to go through and pass every procedure. The interviews are based on the requirements of the post and the questions vary from easy to difficult level. What is DFA, NFA, their differences, features and functionalities and some more similar questions are being asked in interview rounds where prior knowledge of finite automaton or theory is required.

NFA is Nondeterministic Finite Automaton which means that the NFA can exist in, or can leads to transition to many different states at the same time for provided inputs. Here, the transitions are not uniquely determined by their input element or their source state. Reading of input symbols is not needed for every state transition. Every DFAs are NFAs.

DFA is Deterministic Finite Automaton where the DFA can exist in, or can leads to a transition to only one state at a given time for provided inputs. It details the uniqueness of the computation. In branch of computer science (theoretical), theory of computation includes DFA also known as a deterministic finite-state machine. It is an FSM which has been designed to accept or reject only finite strings of symbols. It is an abstract mathematical concept. Also, it is used in software and hardware for getting solutions to specific problems. It recognizes regular languages in order to perform lexical analysis, pattern matching, etc. They are designed from NFAs by incorporating the method of powerset construction.

Difference between NFA and DFA:

  • Deterministic Finite Automaton (DFA) is a type of finite automata where there is only one path possible for specific input for the transition from its present state to the next state. For each input symbol, there is a unique transition. While in Non-Deterministic Finite Automaton (NFA) which is also a type of FA, for a given set of inputs, it is possible to have many paths in order to make the transition from their present or current state to the next states.
  • In DFA, empty String transition cannot be used. But in NFA it is possible.
  • For the purpose of computing, DFA is not explained as separate units but in the form of one machine only. On the other hand, NFA is a set of multiple separate little-sized units which are combined together for computation activities.
  • If the termination state is other than the accepting one, then DFAs reject the string. While NFA rejects it only when all branches do not accept the string or dead.
  • Only one transition state is there for every alphabetic element. But on the other side, there are no requirements of user-specifications for making NFAs react in line to symbols.

This is the basic that one should know all about the details with difference between NFA and DFA in order to perform well in the interviews.