print("hello world".upper(), "HeLLo".lower())upper() / lower().
Python string methods
Strings are immutable, so every method returns a new string (or a list/bool/int). Run any example to see the output.
25 entries
Case
print("hello world".title(), "hello world".capitalize())title() capitalises each word, capitalize() only the first.
print("Straße".casefold() == "STRASSE".casefold())casefold() for case-insensitive comparison.
print("Hello".swapcase())swapcase().
Split & join
print("a,b,,c".split(","))split(sep) keeps empty strings between separators.
print(" many spaces here ".split())split() with no argument splits on runs of whitespace.
print("k=v=w".split("=", 1), "k=v=w".rsplit("=", 1))maxsplit from the left or right.
print("line1\nline2\r\nline3".splitlines())splitlines() handles \n and \r\n.
print("-".join(["2026", "09", "27"]))join() glues an iterable of strings.
print("user@example.com".partition("@"))partition() → (before, sep, after).
Trim & pad
print(repr(" hi \n".strip()), repr("xxhixx".strip("x")))strip() removes whitespace or given chars from both ends.
print("v1.2".removeprefix("v"), "report.csv".removesuffix(".csv"))removeprefix / removesuffix (3.9+).
print("7".zfill(3), "hi".center(8, "*"), "hi".ljust(5) + "|")Padding.
Search & replace
s = "banana"
print(s.find("an"), s.rfind("an"), s.find("x"))find returns index or -1.
s = "banana"
print(s.count("a"), "nan" in s)count() and the in operator.
print("photo.JPG".lower().endswith((".jpg", ".png")))startswith/endswith accept a tuple.
print("a-b-c".replace("-", "+"), "a-b-c".replace("-", "+", 1))replace(old, new, count).
Checks
print("123".isdigit(), "12.5".isdigit(), "abc".isalpha(), "abc1".isalnum())Character-class checks (isdigit is False for "12.5").
print(" ".isspace(), "Hello World".istitle(), "abc".islower())More checks.
print("my_var".isidentifier())Valid Python identifier?
Formatting
name, n = "Ada", 3
print(f"{name} has {n} items")f-string (preferred).
print("{} + {} = {}".format(1, 2, 3))str.format().
print(f"{0.4567:.1%}", f"{42:>6}", f"{255:#x}")Format specs: percent, alignment, hex.
print("tab\tsep".expandtabs(4))expandtabs().
table = str.maketrans("abc", "xyz")
print("aabbcc".translate(table))translate() maps characters.
Frequently asked questions
How do I reverse a string in Python?
Use slicing: s[::-1]. There is no reverse() method on strings because they are immutable.
Why doesn’t s.replace() change my string?
Strings are immutable. replace() returns a new string, so assign it: s = s.replace("a", "b").
split() vs split(" ")?
split() splits on any run of whitespace and drops empty strings. split(" ") splits on each single space and keeps empty strings when there are consecutive spaces.