Regular Expressions
Master pattern matching with regex. Learn to search, validate, and manipulate text using the re module.
Master pattern matching with regex. Learn to search, validate, and manipulate text using the re module. This hands-on tutorial focuses on practical implementation of regular expressions concepts.
Regular Expressions
Regular Expressions (regex) are powerful patterns for matching and manipulating text.
Basic Patterns
| Pattern | Matches | Example |
|---|---|---|
| . | Any character | a.c matches "abc", "a1c" |
| * | 0 or more | ab*c matches "ac", "abc", "abbc" |
| + | 1 or more | ab+c matches "abc", "abbc" (not "ac") |
| ? | 0 or 1 | ab?c matches "ac", "abc" |
| ^ | Start of string | ^Hello matches "Hello world" |
| $ | End of string | world$ matches "Hello world" |
Character Classes
| Pattern | Matches |
|---|---|
| [abc] | a, b, or c |
| [a-z] | Any lowercase letter |
| [A-Z] | Any uppercase letter |
| [0-9] | Any digit |
| \d | Digit (same as [0-9]) |
| \w | Word character (letter, digit, underscore) |
| \s | Whitespace |
| \D | Non-digit |
| \W | Non-word character |
| \S | Non-whitespace |
The re Module
Common Patterns
Email Validation
Phone Number Extraction
Capture Groups
re.sub() - Find and Replace
Regex Flags
Coding Challenge: Log Parser 📋
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Quiz
Quiz
Question 1 of 5What does the + quantifier mean?
Key Takeaways
✅ Regex patterns match text using special syntax.
✅ re.search() finds first match, re.findall() finds all.
✅ Character classes like \d, \w, \s match common patterns.
✅ Capture groups () extract parts of matches.
✅ re.sub() replaces matched text.
What's Next?
In the next lesson, we'll learn about Iterators & Generators - memory-efficient ways to work with sequences.
Keep coding! 🚀