Strings
Strings are immutable sequences of Unicode characters. They offer rich methods for searching, slicing, formatting and manipulation.
Details
Strings can be created with single, double, or triple quotes. They are indexed (0-based) and support slicing s[start:stop]. Because strings are immutable, most operations return new strings. Common methods: .upper(), .lower(), .strip(), .split(), .join(), .replace().
Examples
s = " Hello, World! "
print(s.strip())
print(s[1:6])
parts = "a,b,c".split(",")
print(parts)
print(" - ".join(parts))
name = "khushi"
print(name.title())Useful methods (quick)
| Method | Purpose |
|---|---|
| split() | Split string into list by separator |
| join() | Join iterable into a single string |
| replace() | Replace substring occurrences |
| strip() | Remove leading/trailing whitespace |
Common mistakes
- IndexError when accessing out-of-range indices.
- Trying to mutate a string (e.g.,
s[0] = 'A'— raisesTypeError). - Forgetting to strip newline when comparing user input.
Exercises
- Reverse a string using slicing.
- Given a CSV string, split it and join it with semicolons.
- Write a function that capitalizes each word in a sentence (title case).
Next steps
Move to String Formatting and Regular Expressions for text processing and pattern matching.