7 pat t e r n m at c h I n g w I t h r e g u L a r e X p r e s s I o n s

Practice Questions
1. What is the function that creates 
Regex
objects?
2. Why are raw strings often used when creating 
Regex
objects?
3. What does the 
search()
method return?
4. How do you get the actual strings that match the pattern from a 
Match
object?
5. In the regex created from 
r'(\d\d\d)-(\d\d\d-\d\d\d\d)'
, what does 
group 
0
cover? Group 
1
? Group 
2
?
6. Parentheses and periods have specific meanings in regular expression 
syntax. How would you specify that you want a regex to match actual 
parentheses and period characters?
7. The 
findall()
method returns a list of strings or a list of tuples of 
strings. What makes it return one or the other?
8. What does the 
|
character signify in regular expressions?
9. What two things does the 
?
character signify in regular expressions?
10. What is the difference between the 
+
and 
*
characters in regular 
expressions?
11. What is the difference between 
{3}
and 
{3,5}
in regular expressions?
12. What do the 
\d
, 
\w
, and 
\s
shorthand character classes signify in 
regular expressions?

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Pattern Matching with Regular Expressions
185
13. What do the 
\D
, 
\W
, and 
\S
shorthand character classes signify in 
regular expressions?
14. What is the difference between 
.*
and 
.*?
?
15. What is the character class syntax to match all numbers and 
lowercase letters?
16. How do you make a regular expression case-insensitive?
17. What does the 
.
character normally match? What does it match if 
re.DOTALL
is passed as the second argument to 
re.compile()
?
18. If 
numRegex = re.compile(r'\d+')
, what will 
numRegex.sub('X', '12 drummers, 
11 pipers, five rings, 3 hens')
return?
19. What does passing 
re.VERBOSE
as the second argument to 
re.compile()
allow you to do?
20. How would you write a regex that matches a number with commas for 
every three digits? It must match the following:
• 
'42'
• 
'1,234'
• 
'6,368,745'
but not the following:
• 
'12,34,567'
(which has only two digits between the commas)
• 
'1234'
(which lacks commas)
21. How would you write a regex that matches the full name of someone 
whose last name is Watanabe? You can assume that the first name that 
comes before it will always be one word that begins with a capital letter. 
The regex must match the following:
• 
'Haruto Watanabe'
• 
'Alice Watanabe'
• 
'RoboCop Watanabe'
but not the following:
• 
'haruto Watanabe'
(where the first name is not capitalized)
• 
'Mr. Watanabe'
(where the preceding word has a nonletter character)
• 
'Watanabe'
(which has no first name)
• 
'Haruto watanabe'
(where Watanabe is not capitalized)
22. How would you write a regex that matches a sentence where the first word 
is either Alice, Bob, or Carol; the second word is either eats, pets, or throws; 
the third word is apples, cats, or baseballs; and the sentence ends with a 
period? This regex should be case-insensitive. It must match the following:
• 
'Alice eats apples.'
• 
'Bob pets cats.'
• 
'Carol throws baseballs.'
• 
'Alice throws Apples.'
• 
'BOB EATS CATS.'

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186
Chapter 7
but not the following:
• 
'RoboCop eats apples.'
• 
'ALICE THROWS FOOTBALLS.'
• 
'Carol eats 7 cats.'