Compiler Design Multiple Choice Questions

Compiler Design Multiple Choice Questions

1) Users write the programs in which language?

Low-level Language

High-Level Language

Decimal-Format

Middle-Level Language 

Answer: b. High-Level Language

Explanation: Users write the program in a high-level language because it is easier to use, understand and remember.

2) Which computer program accepts the high-level language and converts it into assembly language?

Interpreter

Linker

Assembler

Compiler 

Answer: d. Compiler

Explanation: Compiler is a computer program that accepts the code written in a high-level language and converts that code into the assembly language.

3) Does the compiler program translate the whole source code in one step?

No

Depends on the Compiler

Don't Know

Yes 

Answer: d. Yes

Explanation: The compiler is that program which translates the whole high-level code into the machine code at once.

4) Which of the following file is an output of the assembler?

Program file

Object file

Data File

Task File 

Answer: b. Object File

Explanation: The object file contains the object code, which is an output of an assembler.

5) Which tool is used for grouping of characters in tokens in the compiler?

Parser

Code optimizer

Code generator

Scanner 

Answer: d. Scanner

Explanation: Scanner is a subroutine which is called by the compiler program. The scanner combines the characters and implements them to produce tokens.

6) What is the linker?

It is always used before the program execution.

It is required to create the load module.

It is the same as the loader

None of the above 

Answer: b. It is required to create the load module.

Explanation: Linker is a program in the compiler which is required to create a load module.

7) Parsing is categorized into how many types?

three types

four types

two types

five types 

Answer: c. two types

Explanation: In the compiler design, the parser is mainly categorized into top-down parsing and bottom-up parsing.

8) In which parsing, the parser constructs the parse tree from the start symbol and transforms it into the input symbol.

Bottom-up parsing

Top-down parsing

None of the above

Both a and b 

Answer: b. Top-Down Parsing

Explanation: Top-down parsing is a technique which constructs the parse tree from the start symbol and transforms it to the input symbol. This type of parsing is also referred to as predictive or recursive parsing.

9) Which derivation is generated by the top-down parser?

Right-most derivation in reverse

Left-most derivation in reverse

Right-most derivation

Left-most derivation 

Answer: d. Left-most derivation

Explanation: Top-down parser generates the left-most derivation. It constructs the parse tree from left to right and constructs the left-most derivation of the specified sentence.

10) Which derivation is generated by the bottom-up parser?

Right-most derivation in reverse

Left-most derivation in reverse

Right-most derivation

Left-most derivation 

Answer: a. Right-most derivation in reverse.

Explanation: Bottom-up parser generates the right-most derivation in reverse. It constructs the parse tree from the input string to the root and tries to construct the right-most derivation of the specified string backward.

11) Which parser is most powerful in the following parsers?

Operator Precedence

SLR

Canonical LR

LALR 

Answer: c. Canonical LR

Explanation: Canonical LR (CLR) is the most powerful parser than LALR and SLR.

12) The output of the lexical analyzer is _______

string character

a syntax tree

a set of RE

a set of tokens 

Answer: d. a set of tokens

Explanation: Lexical analyzer gives the set of tokens as output. The set of tokens contains keywords, separators, literals, identifiers, and operators.

13) From the following grammars, which describes the lexical syntax?

Lexical Grammar

Context-free Grammar

Syntactic Grammar

Regular Grammar 

Answer: a. Lexical Grammar

Explanation: Lexical grammar is a type of grammar which specifies the syntax of tokens.

14) Which grammar gives multiple parse trees for the same string?

Unambiguous

Regular

Ambiguous

All of the above 

Answer: c. Ambiguous

Explanation: Ambiguous grammar is a context-free grammar which gives more than one leftmost or rightmost derivation for the same specified sentence.

15) In Compiler lexical analyzer is used for?

removing comments

removing whitespace

breaking the syntaxes in the set of tokens

All of the mentioned 

Answer: d. All of the mentioned

Explanation: Lexical analyzer is used in the compiler for removing the Whitespace and comments. It is also used in breaking the syntaxes into the set of tokens.

16) Which is considered as the sequence of characters in a token?

Mexeme

Lexeme

Texeme

Pattern 

Answer: b. Lexeme

Explanation: Lexemes are the string of alphanumeric characters in a single token. In the source program, lexemes are characters which are identified by the pattern for a token.

17) Which part of the compiler highly used the grammar concept?

Code optimization

Code generation

Parser

Lexical Analysis 

Answer: c. Parser

Explanation: The concept of grammar is much used in the parser phase of the compiler.

The parser phase is next to the lexical analysis phase in the compiler. Parser generated the parse tree using the predefined grammar. The parser has two different techniques for creating a different parse tree.

18) Which phase of the compiler checks the grammar of the programming?

Code Optimization

Semantic Analysis

Code Generation

Syntax Analysis 

Answer: d. Syntax Analysis

Explanation: Syntax Analysis is the 2nd phase of the compiler, which checks the given input string is the correct syntax of the programming language.

19) Which of the following component is important for semantic analysis?

Yacc

Lex

Symbol Table

Type Checking 

Answer: d. Type checking

Explanation: In the semantic analysis, type checking is an important component because it verifies the program's operations from the semantic conventions.

20) Which phase of the compiler is also known as Scanner?

Syntax Analysis

Lexical Analysis

Semantic Analysis

Code generation 

Answer: b. Lexical Analysis

Explanation: The first part of the compiler (lexical analysis) is also known as a scanner. It scans the characters from the source program and implements them to produce tokens.

21) Which phase of the compiler is also known as Parser?

Code Optimization

Semantic Analysis

Syntax Analysis

Lexical Analysis 

Answer: c. Syntax Analysis

Explanation: The phase of the compiler next to the lexical analysis phase is also known as Parser.

Syntax analysis or parser accepts the tokens produced by the lexical analysis and gives the parse tree in the output.

22) Which of the following parser is a top-down parser?

An LALR parser

A LR parser

Operator precedence parser

Recursive descent parser 

Answer: d. Recursive descent parser

Explanation: Recursive descent parser is a type of top-down parser which generates the parse tree from top to bottom and reads the input string from left to right.

23) Keywords are recognized in a compiler during -

the code generation

the data flow analysis

the lexical analysis of the program

the program parsing 

Answer: c. the lexical analysis of the program

Explanation: Keywords are firstly recognized during the lexical analysis of the program in the compiler.

24) Leaf nodes in a parse tree indicate?

sub-terminals

half-terminals

non-terminals

terminals 

Answer: d. terminals.

Explanation: All the leaf nodes in the parse tree indicate the terminals. And all the interior nodes indicate non-terminals.

25) Which graph describes the basic block and successor relationship?

Control graph

DAG

Flow graph

Hamilton graph 

Answer: c. Flow graph

Explanation: A flow graph is a graph of the compiler which describes the basic blocks and how the program control is passed between the blocks.

26) Which language is accepted by the push-down automata?

Type 0 language

Type 1 language

Type 2 language

Type 3 language 

Answer: c. Type 2 language

Explanation: According to the Chomsky hierarchy, push down automata accepts the Type 2 language, which is used for context-free language.

27) The most general phase of structured grammar is?

Context-sensitive grammar

Context-free grammar

Regular grammar

All of these 

Answer: a. Context Sensitive Grammar

Explanation: Context-sensitive grammar is the most general phase of structured grammar because, in this grammar, the left-hand side and the right side contain the terminals or non-terminals.

28) In the compiler, the function of using intermediate code is:

to improve the register allocation

to increase the error reporting & recovery.

to make semantic analysis easier.

to increase the chances of re-using the machine-independent code optimizer in other compilers. 

Answer: d. to increase the chances of re-using the machine-independent code optimizer in other compilers.

Explanation: After semantic analysis, the intermediate code increases the chances of reusing the machine-independent code optimizer in other compilers.

29) In how many types of optimization can be divided?

two types

three types

four types

five types 

Answer: a. two types

Explanation: The code optimization technique is divided into machine-dependent and machine-independent types.

30) The value of which variable is updated inside the loop by a loop-invariant value?

loop

strength

induction

invariable 

Answer: c. induction

Explanation: The value of the induction variable is updated inside the loop by a loop-invariant value.

31) Which compiler runs on one machine and generates code for multiple machines?

Multipass compiler

Cross compiler

Optimizing compiler

Onepass compiler 

Answer: b. Cross compiler

Explanation: Cross compiler is a compiler which runs on one machine and generates code for more than one machine.

32) Which of the following is not a characteristic of the compiler?

More execution time

Debugging process is slow

The execution takes place after the removal of all syntax errors

Firstly scans the entire program and then transforms it into machine-understandable code 

Answer: a. More execution time

Explanation: The compiler does not take more time to execute. So, more execution time is not a characteristic of the compiler.

33) Which phenomenon happens when the non-terminal on the left side is repeated as the first symbol on the right side?

Left-most derivation

Left recursion

Left factoring

Left parsing 

Answer: b. Left recursion

Explanation: Left recursion is the process in which non-terminal on the left side of the production is the same on the right side as the leftmost symbol.

34) In which derivation the right-most non-terminal symbol is replaced at each step?

Right look ahead

Right claim

Rightmost

Right non-terminal 

Answer: c. Rightmost

Explanation: The rightmost derivation is that derivation of context-free grammar, which replaces the rightmost non-terminal symbol at each step.

35) In which derivation the leftmost non-terminal symbol is replaced at each step?

Left recursion

Left non-terminal

Left pushdown

Leftmost 

Answer: d. Leftmost

Explanation: The leftmost derivation is that derivation of context-free grammar which replaces the leftmost non-terminal symbol at each step.

36) The compiler can detect what type of errors?

neither logical nor grammatical error

logical errors only

grammatical errors only

both grammatical and logical errors 

Answer: c. grammatical errors only.

Explanation: Compiler is a computer program that detects grammatical errors, not logical errors.

37) Which symbol is not related to context-free grammar?

End symbol

Start symbol

Non-terminal symbol

Terminal symbol 

Answer: a. End symbol

Explanation: Context-free grammar is that grammar which consists of the start symbol, set of terminals, set of non-terminal symbols and the set of productions.

38) Which method merges the multiple loops into the single one?

Constant Folding

Loop rolling

Loop fusion or jamming

None of the above 

Answer: c. Loop fusion or Loop jamming

Explanation: Loop fusion is an optimization technique which merges the multiple bodies of loops into a single body. This programming technique may reduce the runtime performance of the program.

39) Which parser is known as the shift-reduce parser?

Bottom-up parser

Top-down parser

Both Top-down and bottom-up

None of the Above 

Answer: a. Bottom-up parser

Explanation: Bottom-up parser in the compiler is also called the shift-reduce parser.

40) Which of the following tree is the pictorial identification of the derivation?

The oct tree

The parse tree

The binary tree

None of the above 

Answer: b. The parse tree

Explanation: The tree which represents the syntactic structure of the string is known as the parse tree. It also indicates the terminal, start symbol, and non-terminal symbols.

41) The full form of YACC is:

Yet Another Computer Computer

Yet Another Computer Compiler

Yet Another Compiler Computer

Yet Another Compiler Compiler 

Answer: d. Yet Another Compiler Compiler

Explanation: The full form of YACC is Yet Another Compiler Compiler, which produces the LALR (1) grammar parser.

42) What type of conflicts can occur in the shift-reduce parsing?

reduce/reduce

shift/reduce

Both shift/reduce and reduce/reduce

None of the above 

Answer: b. Shift/reduce

Explanation: None

43) Which of the following grammar can be translated into DFAs?

Generic Grammar

Left Linear Grammar

Right Liner Grammar

All of the above 

Answer: c. Right Linear Grammar

Explanation: A right linear grammar is that grammar which contains all the non-terminals on the right-hand side at the right ends. This grammar can be simply converted into the DFA.

44) Which algorithm invokes a function GETREG()?

Code motion algorithm

Code optimization algorithm

Intermediate Code

Code generation algorithm 

Answer: d. Code generation algorithm

Explanation: Code generation algorithm invokes the GETREG() function to check the status of available registers and the location where the result should be stored. This function also selects the registers for every memory location.

45) FORTRAN programming language is a _______

Turing language

Context-sensitive language

Context-free language

Regular language 

Answer: b. Context-sensitive language.

Explanation: Context-sensitive languages are those languages which are defined by context-sensitive grammar.

46) The execution time of the code depends on?

the usage of machine idioms

the way the registers are used

the orders in which the computations are performed

All of the mentioned 

Answer: d. All of the mentioned

Explanation: None

47) Which optimization technique is used to reduce the multiple jumps?

Latter optimization technique

Peephole optimization technique

Local optimization technique

Code optimization technique 

Answer: b. Peephole optimization technique

Explanation: The peephole optimization technique is used to reduce the memory footprint and the size of code. It is also used to improve the program performance.

48) Which of the following term is used to keep track of the location where the current values of the name are stored?

Register descriptor

Address descriptor

Allocation descriptor

Flag register 

Answer: b. Address descriptor

Explanation: The address descriptor is a descriptor of the code generator technique, which keeps track of the memory location.

49) Which of the following are labeled by operator symbol?

Root

Interior nodes

Leaves

Nodes 

Answer: b. Interior nodes

Explanation: In the compiler, interior nodes are specified by the operator symbol.

50) DAG is an abbreviation of?

Detecting Acyclic Graph

Data Acyclic Graph

Dynamic Acyclic Graph

Directed Acyclic Graph 

Answer: d. Directed Acyclic Graph

Explanation: DAG is a Directed Acyclic Graph, which is constructed using three address code for optimizing the basic blocks.

51) Which of the following is used in various stages or phases of the compiler?

Records

Program

Symbol Table

Table 

Answer: c. Symbol Table

Explanation: A symbol table is simply a table which is created and maintained by the compiler and used in various phases of the compiler.

52) Which of the following structure has four fields?

Parse tree

Triples

Indirect Triples

Quadruples 

Answer: d. Quadruples

Explanation: Quadruples are a record structure in a compiler with four fields for implementing the three address code.

53) In which of the following tree, the leaf indicates the operand, and the interior node represents the operator.

Syntax tree

Parser tree

Structured tree

Sematic tree 

Answer: a. Syntax tree

Explanation: Syntax tree is a tree in the compiler which represents operands by leaf and operator by interior nodes.

54) Which statement is an abstract form of intermediate code?

3- address

2-address

address

Intermediate code 

Answer: a. 3-address

Explanation: None

55) Which mapping is described by the implementation of the syntax-directed translator?

Parse table

Input

Output

Input-Output 

Answer: d. Input-Output

Explanation: Input-Output is a mapping which is described by the implementation of the syntax-directed translator (SDT).

56) Which of the following function is called the canonical collection of LR(0) item.

FIRST

GOTO

COMPUTE

FOLLOW 

Answer: b. GOTO

Explanation: GOTO is a function that is called for defining the DFA. And, it is called the canonical collection of LR(0) item.

57) Which of the following option is not a function of the shift-reduce parser?

Reduce

Accept

Go

Shift 

Answer: c. Go

Explanation: The shift-reduce parser contains only shift, reduce, error and accept action. That's why Go is not a function of the shift-reduce parser.

58) Which of the following grammar has no two adjacent non-terminals?

Irregular grammar

Regular grammar

Operator

Precedence grammar 

Answer: c. Operator

Explanation: Operator grammar is the grammar that does not contain two adjacent non-terminals on the right side of the production. It is that grammar that defines the mathematical operators.

59) DFA is an abbreviation of.

Non Deterministic Finite set Automata

Deterministic Finite Automata

Non Deterministic Finite Automata

Deterministic Finite set Automata 

Answer: b. Deterministic Finite Automata

Explanation: The full form of DFA is Deterministic Finite Automata. It is also known as Deterministic Finite Acceptor. The automata read only one symbol from the input string at a time.

60) NFA is an abbreviation of.

Non Deterministic Finite set Automata

Deterministic Finite Automata

Non Deterministic Finite Automata

Deterministic Finite set Automata 

Answer: c. Non Deterministic Finite Automata

Explanation: The full form of NFA is Non-Deterministic Finite Automata. It is also known as a Non-Deterministic Finite State-machine. An Automaton gives more than one possible transition of the same state.