Python for Beginners | Feb 04, 2026

Python for Beginners 41: Regular Expressions (re) for Beginners

A beginner guide to Regular Expressions (re) for Beginners, including 10 practical examples and 20 quizzes.

Beginner-Friendly Overview

Regular Expressions (re) for Beginners is an important beginner topic in real Python work.

This lesson keeps the language simple but professional. You will learn what the concept is, why it matters, and how to apply it safely in small projects.

Detailed explanation of Regular Expressions (re) for Beginners:
1. Understand the smallest version first.
2. Practice with short examples.
3. Observe outputs and errors carefully.
4. Refactor names so code reads like plain English.
5. Repeat with small daily exercises.

Hands-On Examples

10 examples
Example 1
datetime now
main.py
1 from datetime import datetime
2 print(datetime.now())
Online Python Editor

Run this example, then change one input and observe what changes.

Example 2
Format datetime
main.py
1 from datetime import datetime
2 print(datetime.now().strftime('%Y-%m-%d %H:%M'))
Online Python Editor

Run this example, then change one input and observe what changes.

Example 3
Timedelta usage
main.py
1 from datetime import date, timedelta
2 print(date.today() + timedelta(days=7))
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Run this example, then change one input and observe what changes.

Example 4
Parse JSON string
main.py
1 import json
2 obj = json.loads('{"name":"Ama"}')
3 print(obj['name'])
Online Python Editor

Run this example, then change one input and observe what changes.

Example 5
Write JSON file
main.py
1 import json
2 with open('user.json','w',encoding='utf-8') as f:
3 json.dump({'name':'Kofi'}, f)
Online Python Editor

Run this example, then change one input and observe what changes.

Example 6
Read JSON file
main.py
1 import json
2 with open('user.json','r',encoding='utf-8') as f:
3 print(json.load(f))
Online Python Editor

Run this example, then change one input and observe what changes.

Example 7
Regex search
main.py
1 import re
2 text = 'Order-1234'
3 m = re.search(r'\d+', text)
4 print(m.group())
Online Python Editor

Run this example, then change one input and observe what changes.

Example 8
Regex email check
main.py
1 import re
2 email = 'a@b.com'
3 print(bool(re.match(r'^[^@]+@[^@]+\.[^@]+$', email)))
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Run this example, then change one input and observe what changes.

Example 9
Regex replace
main.py
1 import re
2 print(re.sub(r'\s+', ' ', 'too many spaces'))
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Run this example, then change one input and observe what changes.

Example 10
Compile regex
main.py
1 import re
2 pattern = re.compile(r'cat')
3 print(bool(pattern.search('my cat')))
Online Python Editor

Run this example, then change one input and observe what changes.

Quiz Section

20 questions
1. What is the main purpose of Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
2. What beginner mistake is most common in Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
3. How would you explain Regular Expressions (re) for Beginners to a non-technical learner?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
4. When should you avoid using Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
5. What output do you expect from a basic Regular Expressions (re) for Beginners example?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
6. How can Regular Expressions (re) for Beginners reduce bugs in a project?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
7. How does Regular Expressions (re) for Beginners improve maintainability?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
8. What real-world scenario needs Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
9. What should you learn before Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
10. What should you learn after Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
11. How do you test code involving Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
12. What naming style helps when writing Regular Expressions (re) for Beginners code?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
13. How can comments clarify Regular Expressions (re) for Beginners examples?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
14. What errors appear most often in Regular Expressions (re) for Beginners work?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
15. How can you debug those errors quickly?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
16. What interview question might test Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
17. What tiny project can help practice Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
18. How can daily repetition help you master Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
19. How do teams benefit when everyone understands Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
20. How do you know you truly understood Regular Expressions (re) for Beginners?
Answer guide: A good answer should define the concept, provide a mini code example, and mention one common mistake.
Practice Homework

1. Re-type all examples manually.
2. Change parameters and predict outputs.
3. Build one mini task using at least three examples.
4. Document what errors you met and how you solved them.

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