Lexical Analysis Questions

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21.

A programmer by mistakes writes a program to multiply two numbers instead of dividing them, how can this error be detected?

A

Compiler

B

Interpreter

C

Compiler or interpreter

D

None of the mentioned

Correct Answer: D

This is a logical error that can

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22.

Lexical analysis is the _______ phase of a compiler

A

first

B

second

C

third

D

fourth

Correct Answer: A

Lexical analysis is the first phase of a compiler

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23.

 lexical analyzer is used to ?

A

remove whitespace

B

removing comments

C

breaks these syntaxes into a series of tokens

D

All of the above

Correct Answer: D

The lexical analyzer breaks these syntaxes into a series of tokens, by removing any whitespace or comments in the source code.

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24.

If the lexical analyzer finds a token invalid then?

A

it generates an exception

B

it generates an warning

C

it generates an error

D

reads the whole program

Correct Answer: C

If the lexical analyzer finds a token invalid, it generates an error.

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25.

When the lexical analyzer read the source-code, it scans the code?

A

line by line

B

word by word

C

letter by letter

D

reads the whole program

Correct Answer: C

When the lexical analyzer read the source-code, it scans the code letter by letter; and when it encounters a whitespace, operator symbol, or special symbols, it decides that a word is completed.

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26.

Which tool/computer program for generating lexical analyzers (scanners or lexers) written by Vern Paxson in C around 1987?

A

FLEX 

B

GLEX

C

CLEX

D

SLEX

Correct Answer: A

FLEX (fast lexical analyzer generator) is a tool/computer program for generating lexical analyzers (scanners or lexers) written by Vern Paxson in C around 1987.

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27.

The function ________ is automatically generated by the flex when it is provided with a .l file

A

flex()

B

yylex()

C

lex()

D

nnlex()

Correct Answer: B

The function yylex() is automatically generated by the flex when it is provided with a .l file

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28.

In the input file, In which section Anything written in this brackets is copied directly to the file lex.yy.c?

A

Rules Section

B

Definition Section

C

User Code Section

D

None of the above

Correct Answer: B

Definition Section: The definition section contains the declaration of variables, regular definitions, manifest constants. In the definition section, text is enclosed in "%{ %}" brackets.

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29.

The rule section is enclosed in?

A

%%

B

$$

C

%%%%

D

$$$$

Correct Answer: C

The rule section is enclosed in ""%% %%"".

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30.

Which symbol table implementation is based on the property of locality of reference?

A

Linear list

B

Search tree

C

Hash Table

D

Self Organisation

Correct Answer: C

Hash table is used as a reference for symbol table because it is efficient.

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