Quiz: Regular Expressions

Test your understanding before moving on. Target: 70% or higher to proceed confidently.

Section 1: Multiple Choice (1 point each)

1. Which re function searches the ENTIRE string and returns the first match?

• A) re.match()
• B) re.search()
• C) re.findall()
• D) re.fullmatch()

2. What does the pattern \d{3} match?

• A) The literal characters \d{3}
• B) Any three characters
• C) Exactly three digits
• D) Three or more digits

3. What is the purpose of the r prefix in r"\bword\b"?

• A) It makes the regex case-insensitive
• B) It creates a raw string so backslashes aren't interpreted as Python escape sequences
• C) It compiles the regex for faster execution
• D) It makes the regex match only whole words

4. Which character class matches any single whitespace character (space, tab, newline)?

• A) \d
• B) \w
• C) \s
• D) \b

5. What does re.findall(r"\b\w+\b", "Hello, World!") return?

• A) ['Hello, World!']
• B) ['Hello', 'World']
• C) ['Hello,', 'World!']
• D) ['H', 'e', 'l', 'l', 'o', 'W', 'o', 'r', 'l', 'd']

6. What is the difference between greedy * and lazy *??

• A) * matches zero or more; *? matches one or more
• B) * matches as many characters as possible; *? matches as few as possible
• C) * is case-sensitive; *? is case-insensitive
• D) * works with any character class; *? only works with .

7. Which function would you use to replace all occurrences of a pattern in a string?

• A) re.search()
• B) re.findall()
• C) re.sub()
• D) re.match()

8. What does (?P<name>\d+) do in a regex pattern?

• A) Matches the literal text "name" followed by digits
• B) Creates a named capture group called "name" that matches one or more digits
• C) Creates a non-capturing group for digits
• D) Matches the word "name" and any following digits

Section 2: True/False with Justification (1 point each)

9. "re.match() checks whether the pattern matches the entire string."

10. "The pattern [^0-9] matches any character that is NOT a digit."

11. "You should always use regex instead of string methods because regex is more powerful."

12. "The pattern \bcat\b would match the word 'cat' inside the word 'concatenate'."

Section 3: Short Answer (2 points each)

13. Write a regex pattern that matches a date in MM/DD/YYYY format where MM is 01-12, DD is 01-31, and YYYY is a four-digit year. Then write it again using named groups for month, day, and year.

r"\d{2}/\d{2}/\d{4}"

r"(?P<month>\d{2})/(?P<day>\d{2})/(?P<year>\d{4})"

14. Explain in your own words what "greedy vs. lazy" matching means. Give a concrete example where using greedy matching produces an unwanted result and lazy matching fixes it.

15. When would you use re.compile() instead of calling re.search() or re.findall() directly? Give one practical scenario.

Section 4: Applied Scenario (3 points)

16. You receive a text file containing mixed-format data. Each line contains a person's information in one of these formats:

John Smith, 42, john@example.com
Jane Doe | age: 35 | jane.doe@test.org
Bob (28) - bob_jones@company.co.uk

Write a Python function using regex that extracts the name, age, and email from each line, regardless of format. Return the data as a list of dictionaries.

import re

def parse_records(lines: list[str]) -> list[dict]:
    results = []
    for line in lines:
        # Extract email (most consistent format)
        email_match = re.search(r"[\w.+-]+@[\w.-]+\.\w{2,}", line)
        email = email_match.group() if email_match else None

        # Extract age (a number, possibly with "age:" prefix)
        age_match = re.search(r"(?:age:\s*)?(\d{1,3})", line)
        age = int(age_match.group(1)) if age_match else None

        # Extract name (alphabetic words at the start)
        name_match = re.match(r"([A-Za-z]+(?:\s+[A-Za-z]+)*)", line)
        name = name_match.group(1) if name_match else None

        results.append({"name": name, "age": age, "email": email})
    return results

Scoring & Next Steps