Lexical Analysis(MCQs)

What is the primary role of lexical analysis in a compiler? a) Parsing syntax errors b) Generating machine code c) Tokenizing the source code d) Optimizing intermediate code Answer: c) Tokenizing the source code Which component of the compiler is responsible for lexical analysis? a) Parser b) Lexical Analyzer c) Code Generator d) Optimizer Answer: b) Lexical Analyzer In lexical analysis, what is a “token”? a) A sequence of characters b) A basic unit of syntax c) An intermediate code representation d) An error message Answer: b) A basic unit of syntax What type of information does a lexical analyzer produce? a) Syntax tree b) Machine code c) Token stream d) Symbol table Answer: c) Token stream Which of the following is not typically a function of lexical analysis? a) Removing comments and whitespace b) Tokenizing input text c) Generating assembly code d) Identifying keywords and identifiers Answer: c) Generating assembly code What is a “lexeme”? a) A type of token b) A sequence of characters that form a token c) A syntax error d) A type of grammar rule Answer: b) A sequence of characters that form a token Which data structure is commonly used to store tokens during lexical analysis? a) Stack b) Queue c) Array d) Linked list Answer: c) Array What is the purpose of a finite state machine (FSM) in lexical analysis? a) To generate machine code b) To parse tokens into syntax trees c) To recognize patterns and sequences in the source code d) To optimize intermediate code Answer: c) To recognize patterns and sequences in the source code Which phase of compilation processes whitespace and comments in the source code? a) Syntax Analysis b) Lexical Analysis c) Semantic Analysis d) Code Generation Answer: b) Lexical Analysis What is the role of regular expressions in lexical analysis? a) They define the syntax rules of the language b) They describe the patterns for tokens c) They generate the abstract syntax tree d) They optimize code execution Answer: b) They describe the patterns for tokens Which of the following is an example of a token type? a) Integer b) Array c) Stack d) Graph Answer: a) Integer What does a lexical analyzer use to differentiate between keywords and identifiers? a) Syntax rules b) Regular expressions c) Context-sensitive rules d) Machine code Answer: b) Regular expressions In lexical analysis, what is the purpose of tokenization? a) To create a syntax tree b) To generate machine code c) To break the input source code into meaningful symbols d) To optimize the performance of the program Answer: c) To break the input source code into meaningful symbols Which of the following is a common output of lexical analysis? a) Abstract syntax tree b) Token stream c) Intermediate code d) Object code Answer: b) Token stream How does a lexical analyzer handle multi-character operators like <= or !=? a) By treating them as separate tokens b) By combining them into a single token c) By ignoring them d) By converting them to machine code Answer: b) By combining them into a single token Which component is responsible for matching regular expressions to the input stream in lexical analysis? a) Syntax analyzer b) Finite state machine c) Code generator d) Optimizer Answer: b) Finite state machine What does a lexical analyzer do with invalid tokens? a) Ignore them b) Generate a syntax error c) Replace them with valid tokens d) Convert them to machine code Answer: b) Generate a syntax error What is the role of a symbol table in lexical analysis? a) To store token patterns b) To manage variable names and their attributes c) To generate intermediate code d) To parse syntax trees Answer: b) To manage variable names and their attributes Which of the following is a common tool used for lexical analysis? a) Bison b) Yacc c) Flex d) Gcc Answer: c) Flex What is the main purpose of removing comments and whitespace during lexical analysis? a) To improve code readability b) To simplify the token stream for further processing c) To optimize the source code d) To generate machine code Answer: b) To simplify the token stream for further processing Which phase of lexical analysis is responsible for handling identifiers? a) Tokenization b) Pattern matching c) Symbol management d) Error handling Answer: c) Symbol management What does a lexical analyzer do when it encounters a string literal? a) Generates a syntax error b) Converts it into a token representing the string c) Replaces it with a regular expression d) Ignores it Answer: b) Converts it into a token representing the string How does a lexical analyzer typically handle reserved keywords? a) Treats them as special tokens b) Converts them to identifiers c) Ignored d) Translates them into machine code Answer: a) Treats them as special tokens Which of the following is a key feature of a lexical analyzer? a) Syntax checking b) Token generation c) Semantic analysis d) Intermediate code generation Answer: b) Token generation What is the role of a regular expression in defining token patterns? a) To create machine code b) To specify how tokens should be recognized c) To generate syntax trees d) To optimize intermediate code Answer: b) To specify how tokens should be recognized What does “lexical scope” refer to in lexical analysis? a) The range within which tokens are valid b) The depth of the syntax tree c) The extent of memory usage d) The range of regular expressions used Answer: a) The range within which tokens are valid Which of the following is not typically handled by lexical analysis? a) Identifiers b) Keywords c) Syntax trees d) Operators Answer: c) Syntax trees What does the “scanner” refer to in lexical analysis? a) The component that performs syntax checking b) The tool that converts tokens into machine code c) The lexical analyzer that reads and tokenizes the input d) The phase that performs semantic analysis Answer: c) The lexical analyzer that reads and tokenizes the input Which type of language construct is directly managed by lexical analysis? a) Control flow statements b) Function definitions c) Basic tokens like keywords and operators d) Data structures Answer: c) Basic tokens like keywords and operators How does lexical analysis handle multi-line comments? a) Converts them into tokens b) Ignores them and removes them from the source code c) Generates syntax errors d) Translates them into intermediate code Answer: b) Ignores them and removes them from the source code What is the main challenge in lexical analysis when dealing with numeric literals? a) Differentiating between integer and floating-point literals b) Generating machine code c) Parsing complex expressions d) Handling syntax errors Answer: a) Differentiating between integer and floating-point literals What role does a “lexer” play in lexical analysis? a) It parses tokens into syntax trees b) It generates intermediate code c) It performs tokenization and produces tokens d) It performs code optimization Answer: c) It performs tokenization and produces tokens Which of the following is a common output format of lexical analysis? a) Assembly code b) Token stream c) Abstract syntax tree d) Intermediate code Answer: b) Token stream Which type of errors does lexical analysis primarily handle? a) Syntax errors b) Semantic errors c) Lexical errors d) Runtime errors Answer: c) Lexical errors What is a “token stream” in the context of lexical analysis? a) A sequence of machine code instructions b) A list of recognized tokens and their attributes c) A sequence of syntax errors d) A set of intermediate representations Answer: b) A list of recognized tokens and their attributes How does a lexical analyzer treat numerical constants? a) Converts them into tokens representing their values b) Ignores them c) Parses them into syntax trees d) Generates error messages Answer: a) Converts them into tokens representing their values What is the purpose of “token classification” in lexical analysis? a) To generate syntax trees b) To categorize tokens into types such as keywords, identifiers, or literals c) To optimize intermediate code d) To perform code generation Answer: b) To categorize tokens into types such as keywords, identifiers, or literals Which type of lexical analyzer tool is used to generate lexical analyzers from regular expressions? a) Yacc b) Flex c) Bison d) Gcc Answer: b) Flex What is the main purpose of handling escape sequences in lexical analysis? a) To handle special characters within string literals b) To generate machine code c) To parse complex expressions d) To create syntax trees Answer: a) To handle special characters within string literals Which phase directly precedes syntax analysis in the compilation process? a) Semantic analysis b) Code optimization c) Lexical analysis d) Code generation Answer: c) Lexical analysis In lexical analysis, what is meant by “lexical unit”? a) A part of the machine code b) A sequence of characters that form a token c) A type of syntax error d) An intermediate code representation Answer: b) A sequence of characters that form a token How does lexical analysis handle nested comments in programming languages? a) Treats them as nested tokens b) Ignores them as invalid syntax c) Removes them and processes the remaining code d) Converts them to machine code Answer: c) Removes them and processes the remaining code Which aspect of source code is not directly analyzed by the lexical analyzer? a) Variable names b) Function names c) Syntax rules d) Operators Answer: c) Syntax rules What is the primary function of the “token table” in lexical analysis? a) To store machine code b) To keep track of recognized tokens and their attributes c) To generate abstract syntax trees d) To optimize intermediate code Answer: b) To keep track of recognized tokens and their attributes What does a lexical analyzer do with identifiers it encounters? a) Converts them to numeric values b) Categorizes them and stores them in a symbol table c) Generates syntax trees d) Translates them to machine code Answer: b) Categorizes them and stores them in a symbol table What is an example of a token type handled by a lexical analyzer? a) Variable declaration b) Expression evaluation c) Operator d) Function call Answer: c) Operator What does a “lexical error” typically indicate? a) Incorrect syntax b) Invalid or unrecognized token c) Semantic mismatch d) Runtime exception Answer: b) Invalid or unrecognized token How does lexical analysis contribute to error reporting? a) By generating runtime error messages b) By providing detailed syntax error reports c) By identifying and reporting invalid tokens d) By optimizing code for performance Answer: c) By identifying and reporting invalid tokens Which tool is used to specify the lexical rules of a language in a more readable format? a) Yacc b) Bison c) Lex d) Gcc Answer: c) Lex What is the role of “lookahead” in lexical analysis? a) To predict future tokens b) To determine the context of the current token c) To handle multi-character tokens d) To generate syntax trees Answer: c) To handle multi-character tokens