6 1 (a) The C programming language distinguishes character constants

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6.1 (a) The C programming language distinguishes

character constants from string constants by

using single quotation marks for characters and double

quotation marks for strings. Thus,

\'c\' is the character c, while \"c\" is a string of length 1

consisting of the single character c.

Why do you think this distinction is made? Is it useful?

(b) Python, on the other hand, uses double quotation

marks for both characters and strings

(thus, \"c\" is either a character or string, depending on

context). Discuss the advantages and

disadvantages of these two approaches.

6.3 Discuss the pros and cons of ignoring or requiring

“white space” (i.e., blanks, end-of-lines, and

tabs) when recognizing tokens.

6.4 Many programming languages (like C) do not allow

nested comments. Why is this requirement

made? Modula-2 and a few other languages do allow

nested comments. Why is this useful?

6.5 (a) Describe the strings that are represented by the

regular expression:

[0-9]+((E|e)(\\+|\\-)?[0-9]+)?

(b) Write a regular expression for C identifiers consisting

of letters, digits, and the underscore

character ‘_’, and starting with a letter or underscore.

Solution

6.1 a) This is design decision, it is useful to clearly identify

for compiler which one is string and char and act

accordingly in terms of memory allocation, operations.

6.1 b) Advantage of having single quotes for both is

programmer doesn\'t need to remember which one to use

for which and get rid of confusion but the disadavntage is

there is no distinctionh and for later point either they have

to cleraly specify (comment) which is char and which is

string.In case that a huge program and memebers were

defined two three days back and programmer foget to

comment then it may lead to appying wrong operations.

6.3v Prons :

1) It becomes easy copy code to different levels (the

programmer has no need to fix the indentation)

2) It is moreconsistent as some of the editors display

whitespace differently.

Cons :

1) It doesn\'t help in reducing inconsistent indentation in

code.

6.4 To ease parsing as if nested comments are not allowed

then compiler doesn\'t have to maintian a stack.

In some languages nested comments are allowed so that a

section of code could be commented out even if it conatins

other comments.

6.5 a) This regular expression defines the scientific

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6.1 (a) The C programming language distinguishes character constants from string constants by using single quotation marks for characters and double quotation marks for strings. Thus, \'c\' is the character c, while \"c\" is a string of length 1 consisting of the single character c. Why do you think this distinction is made? Is it useful? (b) Python, on the other hand, uses double quotation marks for both characters and strings (thus, \"c\" is either a character or string, depending on context). Discuss the advantages and disadvantages of these two approaches. 6.3 Discuss the pros and cons of ignoring or requiring “white space” (i.e., blanks, end-of-lines, and tabs) when recognizing tokens. 6.4 Many programming languages (like C) do not allow nested comments. Why is this requirement made? Modula-2 and a few other languages do allow nested comments. Why is this useful? 6.5 (a) Describ ...
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