Question

Regarding Python.

1.

How would you write a regex that matches the hour of the day from the extracted line shown below? (The highlighted portion)

From [email protected] Sat Jan 5 09:14:16 2008

Question options:

	ˆFrom .+ [0-9] ˆX-.*: [0-9.]+ [0-9]:
	ˆFrom .* [0-9][0-9]:
	ˆFrom .* ('ˆX\S*: ([0-9.]+)', line)

A _____________ sign at the end of the regular expression indicates that the string must end with the specified regex pattern.

Question options:

	question (?)
	caret (^)
	dollar ($)
		0 / 1 point

Which of the following will be a correct match for the regex "F..M"

Question options:

	F!@M
	FRONM
	FOR

Which of the following is used by Unix grep to match a character that is anything other than a space?

Question options:

	"/S"
	"[ˆ ]"
	"/s"

Python uses a ___________algorithm to search for keys in a dictionary?

Question options:

	hash table
	reference list
	search engine

_____________ is a special character that matches any character.

Question options:

	Escape character
	Wild card
	Regular expression

import re

hand = open('mbox-short.txt')

for line in hand:

line = line.rstrip()

if re.search('ˆFrom:.+@', line) :

print line

What is the correct interpretation of the highlighted portion of the script shown above?

Question options:

	The search will match lines that end with "From:", followed by an @ sign, followed by zero or more characters.
	The search will match lines that start with "From:", followed by one or more characters, followed by an @ sign.
	The search will match lines that end with "From:", followed by a plus (+) sign, followed by an @ sign.

Answer 1

Question1

The correct option is C) ˆFrom .* ('ˆX\S*: ([0-9.]+)', line) ,
This is because we need the second parameter which is the strign on which regex is to be applied , also we nned to seacrhc only the hour which is the first two digits and hence the given option

Question 2

The corretc option si option C) dollar ($) ,
caret sign is used to match startign characters and ? is used to match a single character , $ is ised to match ending characters

Question 3

The correct option is option a F!@M

. menas any character except line break so the qiven regex will match any word having 4 characters and so the first option

Question 4

The correct option will be option b[^ ]
^ enclosed in [] means not to include anything mentioned inside the barcket , in this case the space.

Question 5

The correct option i a) hash table

python uses hash table algoritm to search for keys in a dictionary

Question 6

The correct option is b) wild card

In regex wild cards are used to match any character

Question 7

The correct option is b) The search will match lines that start with "From:", followed by one or more characters, followed by an @ sign.

^ meatches the start of strign and .+ means 0 or more characters so option b