1
A context-free grammar consists of terminals, non-terminals, a start symbol and
Correct Answer
productions
☑ MCQ PRACTICE
Compiler Design Unit 2
Practice objective questions for quick revision and examination preparation. Try answering each question before revealing the answer.
Compiler Design MCQs - Unit 2
2
A grammar is ambiguous if
Correct Answer
some string has more than one parse tree
3
Left recursion in a grammar causes a top-down parser to
Correct Answer
go into an infinite loop
4
Eliminating immediate left recursion from A → Aα | β gives
Correct Answer
A → βA′ and A′ → αA′ | ε
5
Left factoring is used to
Correct Answer
make a grammar suitable for predictive parsing
6
Top-down parsing constructs the parse tree
Correct Answer
from the root down to the leaves
7
Bottom-up parsing corresponds to a
Correct Answer
rightmost derivation in reverse
8
In LL(1), the first L stands for scanning the input
Correct Answer
from left to right
9
A predictive parser uses
Correct Answer
a parsing table and a stack
10
FIRST(A) is the set of
Correct Answer
terminals that can begin strings derived from A
11
FOLLOW(A) is the set of
Correct Answer
terminals that can appear immediately to the right of A
12
FOLLOW of the start symbol always contains
Correct Answer
$ (the end marker)
13
The actions of a shift-reduce parser are shift, reduce, accept and
Correct Answer
error
14
A handle is a substring that
Correct Answer
matches the right side of a production and whose reduction is a step in a reverse rightmost derivation
15
In LR(k), the letter R stands for
Correct Answer
constructing a rightmost derivation in reverse
16
Which of the following is the most powerful LR parser?
Correct Answer
Canonical LR (CLR)
17
LALR parsing merges LR(1) states that have the same
Correct Answer
core
18
SLR parsers decide reduce actions using
Correct Answer
FOLLOW sets
19
Yacc is a
Correct Answer
parser generator
20
A shift-reduce conflict occurs when
Correct Answer
the parser cannot decide whether to shift or to reduce
21
Ambiguity in a grammar can be resolved in Yacc by declaring
Correct Answer
precedence and associativity of operators
22
Which of the following is a bottom-up parser?
Correct Answer
SLR parser
23
A recursive-descent parser consists of
Correct Answer
a set of procedures, one for each non-terminal
24
In panic-mode error recovery, the parser
Correct Answer
discards input symbols until a synchronizing token is found
25
A grammar that is suitable for LL(1) parsing must not be
Correct Answer
left-recursive or ambiguous
Fill in the Blanks
26
A context-free grammar consists of terminals, non-terminals, a start symbol and ______.
Correct Answer
productions
27
A grammar that produces more than one parse tree for some string is called ______.
Correct Answer
ambiguous
28
Eliminating left recursion from A → Aα | β gives A′ → αA′ | ______.
Correct Answer
ε
29
In LL(1), the second L stands for a ______ derivation.
Correct Answer
leftmost
30
The ______ of the start symbol always contains the end marker $.
Correct Answer
FOLLOW
31
Bottom-up parsing produces a rightmost derivation in ______.
Correct Answer
reverse
32
A substring that matches the right side of a production and can be reduced is called a ______.
Correct Answer
handle
33
The actions of a shift-reduce parser are shift, reduce, accept and ______.
Correct Answer
error
34
SLR parsers use ______ sets to decide where to place reduce actions.
Correct Answer
FOLLOW
35
Of SLR, LALR and CLR, the most powerful parser is ______.
Correct Answer
CLR (canonical LR)
36
LALR parsers merge LR(1) states that have the same ______.
Correct Answer
core
37
______ is a widely used LALR parser generator.
Correct Answer
Yacc
38
A ______ conflict occurs when the parser cannot decide whether to shift or reduce.
Correct Answer
shift-reduce
39
A recursive-descent parser has one ______ for each non-terminal.
Correct Answer
procedure
40
In panic-mode recovery, the parser discards input ______ until a synchronizing token is found.
Correct Answer
symbols (tokens)