Basics▶

1. Literal Characters

2. The Dot Wildcard

3. Escaping Special Characters

Character Classes▶

4. Character Sets [abc]

5. Character Ranges [a-z]

6. Negated Sets [^abc]

7. Digit Shorthand \d

8. Non-Digit \D

9. Word Characters \w

10. Whitespace \s

Anchors & Boundaries▶

11. Start Anchor ^

12. End Anchor $

13. Word Boundary \b

14. Non-Word Boundary \B

Quantifiers▶

15. Zero or More *

16. One or More +

17. Optional ?

18. Exact Count {n}

19. Range {n,m}

20. Lazy Quantifiers

Groups & Capturing▶

21. Basic Groups ()

22. Alternation |

23. Non-Capturing Groups (?:)

24. Named Groups (?<name>)

25. Backreferences \1

Lookarounds▶

26. Positive Lookahead (?=)

27. Negative Lookahead (?!)

28. Positive Lookbehind (?<=)

29. Negative Lookbehind (?<!)

Real-World Patterns▶

30. Email Validation

31. Phone Numbers

32. URLs

33. IP Addresses

34. Credit Card Numbers

35. Hex Color Codes

36. Dates (ISO Format)

37. Time (24-hour)

38. Passwords

39. HTML Tags

Lesson 1 of 390% Complete

Literal Characters

Match exact characters in text

Key Concept

The simplest regex patterns match literal characters exactly as they appear. For example, cat matches the exact sequence 'cat' in text.

Your Pattern

Test Cases

Your regex should match the green cases and NOT match the gray cases.

✓Should Match (3)

cat✓

The cat sat✓

category✓

✗Should NOT Match (2)

dog✗

CAT✗

Made by Pranav Karra and Claude • Studying for CMPSC 461 at Penn State