Parsing Techniques - LL/LR for Competitive Exam Success

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Parsing Techniques - LL/LR

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Parsing Techniques - LL/LR MCQ & Objective Questions

Understanding Parsing Techniques, specifically LL and LR parsing, is crucial for students preparing for exams. These concepts form the backbone of compiler design and are often featured in objective questions. Practicing MCQs related to Parsing Techniques helps students grasp these essential topics, ensuring better scores in their exams. Engaging with practice questions allows for a deeper understanding of important concepts and enhances exam readiness.

What You Will Practise Here

Fundamentals of LL and LR parsing techniques
Differences between top-down and bottom-up parsing
Construction of LL(1) and LR(0) parsing tables
Understanding grammar types: context-free and regular grammars
Common parsing algorithms and their applications
Handling ambiguities in parsing
Real-world applications of parsing techniques in programming languages

Exam Relevance

Parsing Techniques are frequently included in the syllabus for CBSE, State Boards, and competitive exams like NEET and JEE. Students can expect questions that test their understanding of parsing algorithms, grammar types, and the construction of parsing tables. Common question patterns include multiple-choice questions that require students to identify the correct parsing method or to analyze given grammars.

Common Mistakes Students Make

Confusing LL parsing with LR parsing and their respective applications
Misunderstanding the significance of first and follow sets in LL parsing
Errors in constructing parsing tables, leading to incorrect parsing decisions
Overlooking the importance of eliminating ambiguities in grammars
Failing to recognize the limitations of different parsing techniques

FAQs

Question: What is the main difference between LL and LR parsing?
Answer: LL parsing is a top-down approach, while LR parsing is a bottom-up approach, which affects how they process input strings.

Question: How can I improve my understanding of parsing techniques?
Answer: Regular practice with Parsing Techniques - LL/LR MCQ questions and reviewing key concepts will enhance your understanding and retention.

Start solving practice MCQs on Parsing Techniques - LL/LR today to test your understanding and boost your confidence for upcoming exams. Master these important Parsing Techniques - LL/LR objective questions with answers to excel in your studies!

Q. In an LR parser, what is the purpose of the 'shift' action?

A. To reduce a production.
B. To push a state onto the stack.
C. To pop a state from the stack.
D. To accept the input.

Solution

The 'shift' action in an LR parser moves the next input symbol onto the stack and transitions to a new state.

Correct Answer: B — To push a state onto the stack.

Q. In LR parsing, what is the significance of the 'shift' action?

A. To reduce the current production.
B. To move the input pointer to the next token.
C. To add a new production to the parse tree.
D. To backtrack to a previous state.

Solution

The 'shift' action in LR parsing moves the input pointer to the next token.

Correct Answer: B — To move the input pointer to the next token.

Q. In the context of LL parsing, what does the '1' in LL(1) signify?

A. One lookahead token is used.
B. One leftmost derivation is produced.
C. One parsing table is required.
D. One recursive call is made.

Solution

The '1' in LL(1) indicates that one lookahead token is used to make parsing decisions.

Correct Answer: A — One lookahead token is used.

Q. What does LR stand for in LR parsing?

A. Left-to-right
B. Right-to-left
C. Left-to-right with lookahead
D. Right-to-left with lookahead

Solution

LR parsing stands for Left-to-right parsing with a rightmost derivation in reverse.

Correct Answer: A — Left-to-right

Q. What does the 'reduce' action do in an LR parser?

A. It shifts the next input symbol onto the stack.
B. It pops symbols from the stack and replaces them with a non-terminal.
C. It accepts the input string.
D. It generates an error.

Solution

The 'reduce' action in an LR parser pops a number of symbols from the stack and replaces them with a non-terminal according to a production rule.

Correct Answer: B — It pops symbols from the stack and replaces them with a non-terminal.

Q. What is a common limitation of LL parsers?

A. They cannot handle ambiguous grammars.
B. They require more memory than LR parsers.
C. They can only parse regular languages.
D. They are slower than LR parsers.

Solution

LL parsers cannot handle ambiguous grammars, which limits their applicability.

Correct Answer: A — They cannot handle ambiguous grammars.

Q. What is the main characteristic of LL parsing?

A. It uses a top-down approach.
B. It uses a bottom-up approach.
C. It requires left recursion.
D. It is non-deterministic.

Solution

LL parsing is a top-down parsing technique that processes the input from left to right and constructs a leftmost derivation of the sentence.

Correct Answer: A — It uses a top-down approach.

Q. What is the primary advantage of using LR parsing over LL parsing?

A. Simplicity of implementation.
B. Ability to handle left recursion.
C. Lower memory usage.
D. Faster parsing speed.

Solution

LR parsing can handle left recursion, which is a limitation of LL parsing.

Correct Answer: B — Ability to handle left recursion.

Q. What is the primary purpose of a parsing table in LR parsing?

A. To store the grammar rules.
B. To determine the next action based on the current state and input symbol.
C. To keep track of the parse tree.
D. To optimize the parsing process.

Solution

The parsing table in LR parsing is used to determine the next action based on the current state and input symbol.

Correct Answer: B — To determine the next action based on the current state and input symbol.

Q. What is the role of the parsing table in an LR parser?

A. To store the grammar rules.
B. To determine the next action based on the current state and input symbol.
C. To keep track of the parse tree.
D. To manage memory allocation.

Solution

The parsing table in an LR parser is used to determine the next action (shift, reduce, accept, or error) based on the current state and the next input symbol.

Correct Answer: B — To determine the next action based on the current state and input symbol.

Q. Which of the following grammars can be parsed using LL(1) parsing?

A. Left-recursive grammars
B. Ambiguous grammars
C. Non-left-recursive and unambiguous grammars
D. Context-free grammars only

Solution

LL(1) parsing can only be applied to non-left-recursive and unambiguous grammars.

Correct Answer: C — Non-left-recursive and unambiguous grammars

Q. Which of the following is a key advantage of LR parsing over LL parsing?

A. LR parsing can handle left recursion.
B. LR parsing is simpler to implement.
C. LL parsing can handle more complex grammars.
D. LR parsing requires less memory.

Solution

LR parsing can handle left recursion, which LL parsing cannot.

Correct Answer: A — LR parsing can handle left recursion.

Q. Which of the following is a requirement for an LL(1) parser?

A. The grammar must be left recursive.
B. The grammar must be ambiguous.
C. The grammar must be free of left recursion.
D. The grammar must have multiple left factors.

Solution

An LL(1) parser requires the grammar to be free of left recursion to ensure that it can make decisions based on a single lookahead token.

Correct Answer: C — The grammar must be free of left recursion.

Q. Which of the following is NOT a type of LR parser?

A. SLR
B. LALR
C. LR(1)
D. LL(1)

Solution

LL(1) is not a type of LR parser; it is a type of LL parser.

Correct Answer: D — LL(1)

Q. Which of the following is true about SLR parsing?

A. It uses a single lookahead token.
B. It is a type of LL parsing.
C. It can handle all context-free grammars.
D. It is less powerful than canonical LR parsing.

Solution

SLR parsing is less powerful than canonical LR parsing as it uses a simpler method for constructing the parsing table.

Correct Answer: D — It is less powerful than canonical LR parsing.

Q. Which of the following parsing techniques can handle a larger class of grammars?

A. LL parsing
B. LR parsing
C. Recursive descent parsing
D. Predictive parsing

Solution

LR parsing can handle a larger class of grammars compared to LL parsing, including all deterministic context-free grammars.

Correct Answer: B — LR parsing

Q. Which of the following statements is true about LL and LR parsers?

A. LL parsers are more powerful than LR parsers.
B. LR parsers can handle all LL grammars.
C. LL parsers can handle all LR grammars.
D. Both LL and LR parsers are equivalent in power.

Solution

LR parsers can handle all LL grammars, but not all LR grammars can be parsed by LL parsers.

Correct Answer: B — LR parsers can handle all LL grammars.

Q. Which parsing technique is generally more powerful, LL or LR?

A. LL
B. LR
C. Both are equally powerful.
D. Neither is powerful.

Solution

LR parsing is generally more powerful than LL parsing as it can handle a larger class of grammars.

Correct Answer: B — LR

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