Which of the following statements about token recognition using finite…
2025
Which of the following statements about token recognition using finite automata is true?
Answer: C. Every token defined by a regular expression can be recognized by a Deterministic Finite Automaton (DFA). — In formal language theory, any language defined by a regular expression is a regular language. Kleene's Theorem proves that every regular language can be…
- A.
Finite Automata are not suitable for recognizing operators in source code.
- B.
Lexical analyzers require context-sensitive grammars for accurate token recognition.
- C.
Every token defined by a regular expression can be recognized by a Deterministic Finite Automaton (DFA).
- D.
Only Nondeterministic Finite Automata (NFA) can be used to recognize tokens in a compiler.
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Correct answer: C
In formal language theory, any language defined by a regular expression is a regular language. Kleene's Theorem proves that every regular language can be recognized by both Non-deterministic Finite Automata (NFA) and Deterministic Finite Automata (DFA). Since NFAs can always be converted into equivalent DFAs via subset construction, lexical analyzers (like Lex or Flex) convert token-defining regular expressions into efficient DFAs to scan source code at runtime.