10 Multiple Choice Questions (MCQs) related to Semantic Analysis, useful for UGC NET, SET, and GATE exams:
1. What is the primary function of semantic analysis in a compiler?
A) Checking syntax errors
B) Checking logical errors
C) Checking type mismatches and undefined variables
D) Optimizing the code
Explanation:
Semantic analysis ensures that the program is meaningfully correct by checking type mismatches, undeclared variables, and function usage.
Answer: C) Checking type mismatches and undefined variables
2. Which of the following errors is detected during semantic analysis?
A) Missing semicolons
B) Type mismatches
C) Unrecognized tokens
D) Invalid operator precedence
Explanation:
Semantic analysis checks for type mismatches, undeclared variables, and incompatible function calls.
Answer: B) Type mismatches
3. What is the primary data structure used in semantic analysis?
A) Parse Tree
B) Symbol Table
C) Stack
D) Linked List
Explanation:
The Symbol Table stores information about variables, functions, and types, which is used in semantic analysis.
Answer: B) Symbol Table
4. Which of the following phases directly precedes semantic analysis?
A) Lexical Analysis
B) Syntax Analysis
C) Intermediate Code Generation
D) Code Optimization
Explanation:
Semantic analysis occurs after syntax analysis, ensuring the parsed structure follows semantic rules.
Answer: B) Syntax Analysis
5. What is type checking in semantic analysis?
A) Checking if all variables are initialized
B) Ensuring that operations are performed on compatible data types
C) Detecting syntax errors
D) Converting high-level code into assembly language
Explanation:
Type checking ensures that operations involve compatible data types (e.g., adding an integer to a string is invalid).
Answer: B) Ensuring that operations are performed on compatible data types
6. Which of the following is NOT a part of semantic analysis?
A) Type checking
B) Scope resolution
C) Checking for undeclared variables
D) Parsing tokens
Explanation:
Parsing tokens is part of syntax analysis, not semantic analysis.
Answer: D) Parsing tokens
7. What is scope resolution in semantic analysis?
A) Determining where variables and functions are accessible
B) Checking if brackets are properly closed
C) Finding the execution order of statements
D) Converting source code to machine code
Explanation:
Scope resolution ensures that variables and functions are used within their declared scope.
Answer: A) Determining where variables and functions are accessible
8. What is the role of attribute grammar in semantic analysis?
A) Defines how code is optimized
B) Specifies rules for associating additional information with syntax trees
C) Determines memory allocation for variables
D) Converts source code into an abstract syntax tree
Explanation:
Attribute Grammar extends context-free grammar by adding semantic rules for meaning validation.
Answer: B) Specifies rules for associating additional information with syntax trees
9. Which technique is commonly used for semantic error detection?
A) Finite State Automata
B) Symbol Table Lookup
C) Shift-Reduce Parsing
D) Regular Expressions
Explanation:
Symbol Table Lookup helps check variable declarations, function signatures, and type consistency.
Answer: B) Symbol Table Lookup
10. Which of the following is an example of a semantic error?
A) Using an undefined variable
B) Misspelling a keyword
C) Missing a closing parenthesis
D) Incorrect indentation in Python
Explanation:
Using an undefined variable is a semantic error because it violates program meaning but is syntactically correct.
Answer: A) Using an undefined variable
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