String Methods

Python · Methods reference

Python · Methods reference

📋 Overview

All standard str instance methods (Python 3). Strings are immutable — methods return new strings.

🔧 Methods

Search & test

Method	Returns	Description
`find(sub[, start[, end]])`	int	First index or -1
`rfind(sub[, start[, end]])`	int	Last index or -1
`index(sub[, start[, end]])`	int	Like find but ValueError if missing
`rindex(sub[, start[, end]])`	int	Like rfind but ValueError if missing
`count(sub[, start[, end]])`	int	Non-overlapping occurrences
`startswith(prefix[, start[, end]])`	bool	Prefix test (tuple of prefixes OK)
`endswith(suffix[, start[, end]])`	bool	Suffix test
`isalpha()` / `isdigit()` / …	bool	Character class tests
`isalnum()` / `isascii()` / `isdecimal()`	bool	More classification
`isidentifier()` / `islower()` / `isupper()`	bool	Identifier / case checks
`isnumeric()` / `isprintable()` / `isspace()`	bool	Numeric / printable / whitespace
`istitle()`	bool	Title-case words

Transform & format

Method	Description
`lower()` / `upper()` / `casefold()`	Case conversion (casefold for Unicode)
`capitalize()` / `title()` / `swapcase()`	Capitalization variants
`strip([chars])` / `lstrip` / `rstrip`	Trim whitespace or chars
`removeprefix(p)` / `removesuffix(s)`	Remove prefix/suffix if present (3.9+)
`replace(old, new[, count])`	Substring replace
`translate(table)`	Character mapping via str.maketrans
`maketrans(x, y[, z])`	Static: build translation table
`format(args, *kwargs)`	Format string with placeholders
`format_map(mapping)`	Format using mapping only
`encode(encoding=…, errors=…)`	Bytes encoding (utf-8 default)
`split(sep=None, maxsplit=-1)`	Split into list
`rsplit(sep=None, maxsplit=-1)`	Split from right
`splitlines([keepends])`	Split on line boundaries
`join(iterable)`	Join strings with self as separator
`partition(sep)` / `rpartition(sep)`	Split into (head, sep, tail)
`center(width[, fillchar])`	Center pad
`ljust(width[, fillchar])` / `rjust`	Left/right pad
`zfill(width)`	Zero-fill numeric strings
`expandtabs([tabsize])`	Tabs to spaces

💡 Examples

See parent topic notes for runnable snippets; this page is the complete method index.

⚠️ Pitfalls

Mutating methods return None in Python — do not chain sort() / reverse() expecting a new list.
Default JS sort() compares strings — pass (a,b) => a-b for numbers.
SQL function names differ by dialect — verify Postgres vs MySQL docs.
Django QuerySet.update() skips save() signals and auto auto_now fields on models.

Set Methods

Python · Methods reference

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📋 Overview 🔧 Methods Search & test Transform & format 💡 Examples ⚠️ Pitfalls 🔗 Related