Mastering Deterministic Finite State Automata
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Questions and Answers

Which part of a language processor is responsible for syntax analysis?

  • The regular grammar
  • The parser (correct)
  • The lexical analyzer
  • The finite automaton

    • Based on the text, what does BNF stand for?

  • Basic Normal Form
  • Binary Number Format
  • Breadth-First Notation
  • Backus-Naur Form (correct)

    • What are the advantages of using BNF to describe syntax?

  • It provides a clear and concise syntax description (correct)
  • It simplifies the lexical analyzer
  • It is based on a regular grammar
  • It allows for easy maintenance of parsers

    • Why is it beneficial to separate lexical and syntax analysis?

    <p>To ensure portability of the parser</p> Signup and view all the answers

    What is the main purpose of a lexical analyzer?

    <p>To generate tokens from lexemes</p> Signup and view all the answers

    What is a lexeme in the context of lexical analysis?

    <p>A substring of the source program</p> Signup and view all the answers

    What does a lexical analyzer transform?

    <p>Characters into tokens</p> Signup and view all the answers

    Which of the following statements is true about a Deterministic Finite State Automaton (DFSA)?

    <p>A DFSA can have at most one outgoing arc from a state for each input symbol.</p> Signup and view all the answers

    What is the purpose of the state transition function in a Finite State Automaton?

    <p>To label the arcs in the state diagram.</p> Signup and view all the answers

    Which of the following is an example of a valid regular expression?

    <p>(a+b)*c</p> Signup and view all the answers

    What is the purpose of using character classes in a state diagram?

    <p>To combine transitions and simplify the state diagram.</p> Signup and view all the answers

    What is the role of look-ahead in tokenizing a language?

    <p>To recognize patterns that are not part of the current token.</p> Signup and view all the answers

    How are conflicts between tokens with proper substrings resolved in lexical analysis?

    <p>By considering the longest match as the correct token.</p> Signup and view all the answers

    What is the purpose of implementing a push-back mechanism in tokenization?

    <p>To handle conflicts between tokens with proper substrings.</p> Signup and view all the answers

    Which of the following is NOT one of the approaches to building a lexical analyzer?

    <p>Write a program that directly implements the tokens without using any formal description or state diagram</p> Signup and view all the answers

    Which of the following statements about regular grammars is true?

    <p>Regular grammars are useful in expressing and recognizing tokens</p> Signup and view all the answers

    Which of the following is an example of a regular expression metacharacter?

    <p>.</p> Signup and view all the answers

    Which of the following regular expressions matches a floating point number?

    <p>[0-9]*.[0-9]+</p> Signup and view all the answers

    Which of the following statements about regular expression matching is true?

    <p>There are libraries that compile regular expressions and use them to match strings</p> Signup and view all the answers

    Which of the following is an example of a finite state automaton (FSA)?

    <p>A program that implements a state diagram</p> Signup and view all the answers

    What is the purpose of the start state in a finite state automaton?

    <p>To represent the set of all possible tokens</p> Signup and view all the answers

    Which function is used to get the next character of input, determine its class, and put it in nextChar?

    <p>getChar()</p> Signup and view all the answers

    What is the purpose of the lex() function?

    <p>To read a token at a time and match as you read the tokens</p> Signup and view all the answers

    What is the purpose of the addChar() function?

    <p>To add the character from nextChar into the place where the lexeme is being accumulated</p> Signup and view all the answers

    What does the int lexLen variable represent in the code?

    <p>The length of the lexeme</p> Signup and view all the answers

    What does the int token variable represent in the code?

    <p>The token type</p> Signup and view all the answers

    What does the int nextToken variable represent in the code?

    <p>The next token type</p> Signup and view all the answers

    What is the purpose of the getNonBlank() function?

    <p>To skip over all the blank spaces</p> Signup and view all the answers

    What is the purpose of the lookup() function?

    <p>To determine whether the string in lexeme is a reserved word</p> Signup and view all the answers

    What does the define UNKNOWN 99 represent in the code?

    <p>An unknown character class</p> Signup and view all the answers

    Which of the following is a characteristic of grammars that disallows top-down parsing?

    <p>Pairwise disjointness</p> Signup and view all the answers

    What is the purpose of left factoring in parsing?

    <p>To determine the correct right-hand side of a rule</p> Signup and view all the answers

    What does the pairwise disjointness test check for in grammars?

    <p>Pairwise disjointness</p> Signup and view all the answers

    What is the purpose of the LL Grammar Class in parsing?

    <p>To modify a grammar</p> Signup and view all the answers

    Which of the following is a characteristic of a top-down parser?

    <p>It produces the parse tree in a leftmost derivation order.</p> Signup and view all the answers

    What is the purpose of a bottom-up parser?

    <p>To produce the parse tree in a rightmost derivation order.</p> Signup and view all the answers

    Which of the following is a characteristic of terminal symbols in a grammar?

    <p>They are lowercase letters at the beginning of the alphabet.</p> Signup and view all the answers

    What is the purpose of the lexeme in lexical analysis?

    <p>To add the character from nextChar into the lexeme being accumulated.</p> Signup and view all the answers

    Which of the following is NOT one of the three approaches to building a lexical analyzer?

    <p>Use a regular expression to automatically generate a lexical analyzer</p> Signup and view all the answers

    Which of the following is NOT a metacharacter in regular expressions?

    <p>M</p> Signup and view all the answers

    What is the purpose of the start state in a finite state automaton (FSA)?

    <p>To represent the set of all possible tokens</p> Signup and view all the answers

    Which of the following statements is true about a Deterministic Finite State Automaton (DFSA)?

    <p>It can have non-deterministic behavior</p> Signup and view all the answers

    Which of the following statements is true about a Deterministic Finite State Automaton (DFSA)?

    <p>A DFSA can have at most one outgoing arc from a state for each input symbol.</p> Signup and view all the answers

    What is the purpose of the lookup() function in lexical analysis?

    <p>To determine if a possible identifier is a reserved word.</p> Signup and view all the answers

    What is the role of look-ahead in tokenizing a language?

    <p>To determine if a token has ended without looking at further characters.</p> Signup and view all the answers

    What does a lexical analyzer transform?

    <p>Regular expressions into finite state automata.</p> Signup and view all the answers

    Which of the following is NOT one of the most common top-down parsing algorithms?

    <p>EBNF</p> Signup and view all the answers

    What is the purpose of the term() function in recursive-descent parsing?

    <p>To parse expressions with multiple terms</p> Signup and view all the answers

    What does the factor() function do in recursive-descent parsing?

    <p>Parses nonterminal symbols in the RHS</p> Signup and view all the answers

    What is the purpose of the expr() function in recursive-descent parsing?

    <p>To parse simple expressions</p> Signup and view all the answers

    Which of the following is an example of a bottom-up parsing algorithm?

    <p>LR</p> Signup and view all the answers

    What is the time complexity of parsers that work for any unambiguous grammar?

    <p>O(n3)</p> Signup and view all the answers

    Which part of the parsing problem involves finding the correct RHS in a right-sentential form to reduce?

    <p>Handle</p> Signup and view all the answers

    What is the most common bottom-up parsing approach?

    <p>Shift-reduce parsing</p> Signup and view all the answers

    What trade-off is made when using parsers that only work for a subset of all unambiguous grammars?

    <p>Generality for efficiency</p> Signup and view all the answers

    What is the time complexity of parsers used in commercial compilers?

    <p>O(n)</p> Signup and view all the answers

    Which part of a language processor is responsible for syntax analysis?

    <p>Syntax analyzer</p> Signup and view all the answers

    Which of the following is an example of a regular expression metacharacter?

    <ul> <li></li> </ul> Signup and view all the answers

    What is the main purpose of a lexical analyzer?

    <p>To transform characters into tokens</p> Signup and view all the answers

    What are the advantages of using BNF to describe syntax?

    <p>All of the above</p> Signup and view all the answers

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