Error handling during parsing and code generation(MCQs)

What is the primary purpose of error handling in parsers? a) To debug code b) To optimize the code c) To detect and recover from syntactical errors d) To execute the code faster Answer: c) To detect and recover from syntactical errors What type of error occurs when a parser encounters an undefined variable? a) Syntax Error b) Semantic Error c) Lexical Error d) Runtime Error Answer: b) Semantic Error Which of the following is a common error-handling technique used in parsing? a) Backtracking b) Panic-mode recovery c) Semantic analysis d) Code optimization Answer: b) Panic-mode recovery Which of these errors can be detected by a lexical analyzer? a) Division by zero b) Unmatched parentheses c) Invalid token d) Type mismatch Answer: c) Invalid token In error recovery, what does “panic mode” imply? a) Discarding input until a specific set of tokens is encountered b) Halting the compilation c) Debugging automatically d) Issuing a warning without stopping the process Answer: a) Discarding input until a specific set of tokens is encountered Which error recovery technique replaces the erroneous input with a set of predefined tokens? a) Phrase-level recovery b) Error productions c) Panic mode d) Global correction Answer: a) Phrase-level recovery What is a semantic error? a) Misspelled variable name b) Invalid token format c) Logical inconsistency in the program d) Incorrect use of programming syntax Answer: c) Logical inconsistency in the program Which of the following errors is typically detected during code generation? a) Type mismatch b) Missing semicolon c) Invalid variable name d) Runtime error Answer: a) Type mismatch What kind of error is encountered when a function is called with the wrong number of arguments? a) Syntax Error b) Semantic Error c) Lexical Error d) Logical Error Answer: b) Semantic Error Which error detection technique involves maintaining a set of error productions in the grammar? a) Global correction b) Backtracking c) Error productions d) Panic mode Answer: c) Error productions How does backtracking help in error handling during parsing? a) By automatically debugging the code b) By rolling back to a previously valid state c) By providing optimization suggestions d) By speeding up the parsing process Answer: b) By rolling back to a previously valid state Which phase of the compiler typically reports the highest number of errors? a) Lexical analysis b) Semantic analysis c) Code generation d) Parsing Answer: d) Parsing What is a “semantic error” during parsing? a) Misuse of an operator b) Invalid variable name c) Undefined variable usage d) Missing semicolon Answer: c) Undefined variable usage What does “panic mode” error recovery do in LR parsing? a) Recompiles the code b) Deletes tokens until a synchronizing token is found c) Automatically fixes the code d) Reports error but continues the parsing Answer: b) Deletes tokens until a synchronizing token is found Which error recovery technique makes minimal changes to the source code to continue parsing? a) Global correction b) Panic mode c) Phrase-level recovery d) Backtracking Answer: a) Global correction Which of the following is true for syntax-directed translation? a) It ignores semantic errors b) It includes error detection during parsing c) It is purely based on lexical tokens d) It skips the code generation phase Answer: b) It includes error detection during parsing In bottom-up parsing, what error-handling mechanism is commonly used? a) Top-down recovery b) Error productions c) Shift-reduce error correction d) Panic mode recovery Answer: d) Panic mode recovery Which of the following cannot be detected at the lexical analysis phase? a) Unmatched parentheses b) Invalid identifier c) Type mismatch d) Unterminated string literal Answer: c) Type mismatch Which of the following is not a type of parsing error? a) Semantic error b) Syntactic error c) Lexical error d) Memory error Answer: d) Memory error What is a common way to handle errors during code generation? a) Ignoring them b) Using optimization techniques c) Emitting code for error handling routines d) Disabling the parser Answer: c) Emitting code for error handling routines When a parser detects an error, what is the next best step? a) Stop the parsing process b) Issue a message and attempt recovery c) Skip the remaining input d) Restart the entire parsing process Answer: b) Issue a message and attempt recovery Which technique allows skipping over erroneous tokens to resume parsing? a) Error correction b) Backtracking c) Panic-mode recovery d) Syntax tree modification Answer: c) Panic-mode recovery What is a lexical error? a) Using a variable before declaration b) Incorrectly formed tokens c) Dividing by zero d) Passing incorrect parameters to a function Answer: b) Incorrectly formed tokens A semantic analyzer checks for which type of error? a) Syntactical errors b) Logical errors c) Type consistency errors d) Token mismatch errors Answer: c) Type consistency errors What is “phrase-level recovery”? a) Recovering from syntactical errors by inserting or deleting tokens b) Ignoring certain blocks of code c) Jumping to another part of the code d) Rewriting the entire program Answer: a) Recovering from syntactical errors by inserting or deleting tokens Which error-handling technique uses a “synchronizing token” to recover from errors? a) Error productions b) Panic-mode recovery c) Backtracking d) Phrase-level recovery Answer: b) Panic-mode recovery In the context of parsing, what is meant by “context-free grammar”? a) A grammar without rules b) A grammar that defines syntax rules c) A grammar that handles all errors automatically d) A grammar without semantic checks Answer: b) A grammar that defines syntax rules Which of the following can a parser not recover from? a) Missing semicolon b) Syntax errors c) Semantic errors d) Infinite loops Answer: d) Infinite loops What is a syntax error? a) Logical error in the code b) Mismatch between expected and actual grammar tokens c) Incorrect data types used d) Runtime error caused by memory issues Answer: b) Mismatch between expected and actual grammar tokens What is the role of a “symbol table” in error detection? a) Storing runtime errors b) Keeping track of variables and types c) Handling syntactical errors d) Detecting lexical errors Answer: b) Keeping track of variables and types Which of the following can detect division by zero at runtime? a) Lexical analyzer b) Semantic analyzer c) Code generation d) Runtime environment Answer: d) Runtime environment Which phase of the compiler is responsible for detecting lexical errors? a) Lexical analysis b) Syntax analysis c) Semantic analysis d) Code generation Answer: a) Lexical analysis What is the purpose of error productions in a grammar? a) To fix syntactical mistakes automatically b) To recover from errors by adding erroneous rules to the grammar c) To remove problematic tokens d) To optimize the parsing process Answer: b) To recover from errors by adding erroneous rules to the grammar What happens when a parser encounters a token that does not belong to the grammar? a) It halts execution b) It skips the token c) It reports an error and recovers d) It replaces the token with a default one Answer: c) It reports an error and recovers Which of the following is an example of a recoverable error in parsing? a) Missing closing parenthesis b) Infinite loop c) Segmentation fault d) Memory leak Answer: a) Missing closing parenthesis Which type of error is checked during type checking? a) Lexical error b) Syntax error c) Semantic error d) Logical error Answer: c) Semantic error How is an “undeclared variable” error classified? a) Syntax error b) Lexical error c) Semantic error d) Logical error Answer: c) Semantic error Which phase comes after syntax analysis in a typical compiler pipeline? a) Code generation b) Lexical analysis c) Semantic analysis d) Error recovery Answer: c) Semantic analysis What kind of error does “type mismatch” fall under? a) Lexical error b) Syntax error c) Semantic error d) Logical error Answer: c) Semantic error Which phase detects “undeclared identifier” errors? a) Lexical analysis b) Semantic analysis c) Syntax analysis d) Code generation Answer: b) Semantic analysis Which of the following is used for error handling in predictive parsing? a) Backtracking b) Parsing table c) Panic mode recovery d) Code optimization Answer: c) Panic mode recovery Which of the following errors are detected at compile time? a) Array out-of-bounds b) Division by zero c) Syntax errors d) Null pointer dereferencing Answer: c) Syntax errors How does the parser handle missing semicolons in error recovery? a) It issues a warning and continues b) It backtracks to a safe point c) It inserts the missing semicolon and continues parsing d) It halts the compilation Answer: c) It inserts the missing semicolon and continues parsing What is “local error recovery” in parsing? a) Automatically fixing the error at the point of detection b) Recovering by skipping multiple tokens c) Using predefined rules for error recovery d) Using the closest valid phrase to recover Answer: a) Automatically fixing the error at the point of detection Which error recovery strategy is most commonly used in YACC? a) Backtracking b) Global correction c) Panic mode recovery d) Phrase-level recovery Answer: c) Panic mode recovery What type of error is caused by using a data type incorrectly in an expression? a) Syntax error b) Lexical error c) Semantic error d) Runtime error Answer: c) Semantic error Which of the following best defines “phrase-level error recovery”? a) It stops parsing upon detecting the error b) It tries to recover by inserting or deleting symbols c) It requires human intervention to correct errors d) It performs full code recompilation Answer: b) It tries to recover by inserting or deleting symbols When does a parser generate an error message? a) When it detects a token mismatch b) During code optimization c) During lexical analysis d) After successful parsing Answer: a) When it detects a token mismatch Which of these error-handling techniques attempts to minimize disruptions in parsing? a) Error productions b) Global correction c) Backtracking d) Panic mode Answer: b) Global correction What kind of errors do lexical analyzers not detect? a) Misspelled keywords b) Unclosed strings c) Type mismatches d) Invalid identifiers Answer: c) Type mismatches