Python String Manipulation Functions — Full Reference

Every built-in method available on Python's str type, with a description and 2 code examples for each.

1. `capitalize()`

Returns a copy of the string with the first character capitalized and the rest lowercased.

# Example 1
s = "hello WORLD"
print(s.capitalize())  # Output: "Hello world"

# Example 2
title = "python programming"
print(title.capitalize())  # Output: "Python programming"

2. `casefold()`

Returns an aggressively lowercased version of the string, used for caseless matching (stronger than lower(), handles special Unicode cases like German ß).

# Example 1
s = "HELLO"
print(s.casefold())  # Output: "hello"

# Example 2
german = "Straße"
print(german.casefold())  # Output: "strasse"

3. `center()`

Centers the string within a specified width, padding with a character (default is space).

# Example 1
s = "hi"
print(s.center(10))  # Output: "    hi    "

# Example 2
s = "menu"
print(s.center(12, "*"))  # Output: "****menu****"

4. `count()`

Returns the number of non-overlapping occurrences of a substring.

# Example 1
s = "banana"
print(s.count("a"))  # Output: 3

# Example 2
sentence = "the cat sat on the mat"
print(sentence.count("the"))  # Output: 2

5. `encode()`

Encodes the string into bytes using the specified encoding (default UTF-8).

# Example 1
s = "hello"
print(s.encode())  # Output: b'hello'

# Example 2
s = "café"
print(s.encode("utf-8"))  # Output: b'caf\xc3\xa9'

6. `endswith()`

Checks whether the string ends with the specified suffix (or tuple of suffixes).

# Example 1
filename = "report.pdf"
print(filename.endswith(".pdf"))  # Output: True

# Example 2
filename = "photo.png"
print(filename.endswith((".jpg", ".png", ".gif")))  # Output: True

7. `expandtabs()`

Replaces tab characters (\t) with spaces, up to a specified tab size (default 8).

# Example 1
s = "a\tb\tc"
print(s.expandtabs(4))  # Output: "a   b   c"

# Example 2
s = "name\tage\tcity"
print(s.expandtabs())  # Output: "name    age     city"

8. `find()`

Returns the lowest index of a substring, or -1 if not found.

# Example 1
s = "hello world"
print(s.find("world"))  # Output: 6

# Example 2
s = "hello world"
print(s.find("xyz"))  # Output: -1

9. `format()`

Formats a string using placeholders {} filled with the given arguments.

# Example 1
name, age = "Kalyan", 25
print("My name is {} and I am {} years old.".format(name, age))
# Output: "My name is Kalyan and I am 25 years old."

# Example 2
print("{0} scored {1:.2f}%".format("Alice", 92.567))
# Output: "Alice scored 92.57%"

10. `format_map()`

Similar to format(), but takes a single dictionary/mapping for substitutions.

# Example 1
data = {"name": "Sam", "job": "Engineer"}
print("{name} works as an {job}".format_map(data))
# Output: "Sam works as an Engineer"

# Example 2
class Default(dict):
    def __missing__(self, key):
        return "N/A"

print("City: {city}".format_map(Default(name="Sam")))
# Output: "City: N/A"

11. `index()`

Like find(), but raises ValueError if the substring is not found.

# Example 1
s = "hello world"
print(s.index("world"))  # Output: 6

# Example 2
s = "hello world"
try:
    print(s.index("xyz"))
except ValueError as e:
    print(f"Error: {e}")  # Output: Error: substring not found

12. `isalnum()`

Returns True if all characters are alphanumeric (letters or digits) and there is at least one character.

# Example 1
print("Python3".isalnum())  # Output: True

# Example 2
print("Hello World!".isalnum())  # Output: False (space and ! are not alnum)

13. `isalpha()`

Returns True if all characters are alphabetic and there is at least one character.

# Example 1
print("Hello".isalpha())  # Output: True

# Example 2
print("Hello123".isalpha())  # Output: False

14. `isascii()`

Returns True if all characters are ASCII.

# Example 1
print("Hello".isascii())  # Output: True

# Example 2
print("café".isascii())  # Output: False

15. `isdecimal()`

Returns True if all characters are decimal digits (0-9 form only, no superscripts/fractions).

# Example 1
print("12345".isdecimal())  # Output: True

# Example 2
print("12.5".isdecimal())  # Output: False (decimal point not allowed)

16. `isdigit()`

Returns True if all characters are digits, including some non-decimal digit forms (e.g., superscripts).

# Example 1
print("123".isdigit())  # Output: True

# Example 2
print("²³".isdigit())  # Output: True (superscript digits count)

17. `isidentifier()`

Returns True if the string is a valid Python identifier (variable name).

# Example 1
print("variable_name".isidentifier())  # Output: True

# Example 2
print("2fast".isidentifier())  # Output: False (cannot start with a digit)

18. `islower()`

Returns True if all cased characters are lowercase and there is at least one cased character.

# Example 1
print("hello world".islower())  # Output: True

# Example 2
print("Hello World".islower())  # Output: False

19. `isnumeric()`

Returns True if all characters are numeric, including fractions and Unicode numerals (broader than isdigit()).

# Example 1
print("12345".isnumeric())  # Output: True

# Example 2
print("½".isnumeric())  # Output: True

20. `isprintable()`

Returns True if all characters are printable (no control characters like \n or \t).

# Example 1
print("Hello World".isprintable())  # Output: True

# Example 2
print("Hello\nWorld".isprintable())  # Output: False

21. `isspace()`

Returns True if all characters are whitespace and there is at least one character.

# Example 1
print("   ".isspace())  # Output: True

# Example 2
print("  a  ".isspace())  # Output: False

22. `istitle()`

Returns True if the string is titlecased (each word starts with an uppercase letter, followed by lowercase).

# Example 1
print("Hello World".istitle())  # Output: True

# Example 2
print("Hello world".istitle())  # Output: False

23. `isupper()`

Returns True if all cased characters are uppercase and there is at least one cased character.

# Example 1
print("HELLO".isupper())  # Output: True

# Example 2
print("Hello".isupper())  # Output: False

24. `join()`

Joins an iterable of strings using the current string as a separator.

# Example 1
words = ["Python", "is", "awesome"]
print(" ".join(words))  # Output: "Python is awesome"

# Example 2
letters = ["a", "b", "c"]
print("-".join(letters))  # Output: "a-b-c"

25. `ljust()`

Left-justifies the string within a given width, padding on the right (default space).

# Example 1
s = "cat"
print(s.ljust(10, "."))  # Output: "cat......."

# Example 2
s = "id"
print(s.ljust(5) + "|")  # Output: "id   |"

26. `lower()`

Converts all characters in the string to lowercase.

# Example 1
s = "HELLO WORLD"
print(s.lower())  # Output: "hello world"

# Example 2
email = "User@EXAMPLE.com"
print(email.lower())  # Output: "user@example.com"

27. `lstrip()`

Removes leading whitespace (or specified characters) from the string.

# Example 1
s = "   hello"
print(s.lstrip())  # Output: "hello"

# Example 2
s = "xxxhello"
print(s.lstrip("x"))  # Output: "hello"

28. `maketrans()`

Creates a translation table to be used with translate(), mapping characters to replacements.

# Example 1
table = str.maketrans("abc", "xyz")
print("abcdef".translate(table))  # Output: "xyzdef"

# Example 2
table = str.maketrans("", "", "aeiou")  # delete vowels
print("hello world".translate(table))  # Output: "hll wrld"

29. `partition()`

Splits the string at the first occurrence of a separator, returning a 3-tuple: (before, separator, after).

# Example 1
s = "key=value"
print(s.partition("="))  # Output: ('key', '=', 'value')

# Example 2
s = "no-separator-here"
print(s.partition(":"))  # Output: ('no-separator-here', '', '')

30. `removeprefix()`

Removes a specified prefix from the string, if present (Python 3.9+).

# Example 1
s = "unhappy"
print(s.removeprefix("un"))  # Output: "happy"

# Example 2
url = "https://example.com"
print(url.removeprefix("https://"))  # Output: "example.com"

31. `removesuffix()`

Removes a specified suffix from the string, if present (Python 3.9+).

# Example 1
filename = "report.txt"
print(filename.removesuffix(".txt"))  # Output: "report"

# Example 2
s = "playing"
print(s.removesuffix("ing"))  # Output: "play"

32. `replace()`

Replaces all occurrences of a substring with another substring.

# Example 1
s = "I like cats"
print(s.replace("cats", "dogs"))  # Output: "I like dogs"

# Example 2
s = "aaaa"
print(s.replace("a", "b", 2))  # Output: "bbaa" (limit replacements to 2)

33. `rfind()`

Returns the highest index of a substring, or -1 if not found (searches from the right).

# Example 1
s = "hello world hello"
print(s.rfind("hello"))  # Output: 12

# Example 2
s = "abcabc"
print(s.rfind("z"))  # Output: -1

34. `rindex()`

Like rfind(), but raises ValueError if the substring is not found.

# Example 1
s = "hello world hello"
print(s.rindex("hello"))  # Output: 12

# Example 2
s = "abcabc"
try:
    print(s.rindex("z"))
except ValueError as e:
    print(f"Error: {e}")  # Output: Error: substring not found

35. `rjust()`

Right-justifies the string within a given width, padding on the left (default space).

# Example 1
s = "42"
print(s.rjust(5, "0"))  # Output: "00042"

# Example 2
s = "cat"
print(s.rjust(10) + "|")  # Output: "       cat|"

36. `rpartition()`

Splits the string at the last occurrence of a separator, returning a 3-tuple: (before, separator, after).

# Example 1
path = "/usr/local/bin"
print(path.rpartition("/"))  # Output: ('/usr/local', '/', 'bin')

# Example 2
s = "no-separator-here"
print(s.rpartition(":"))  # Output: ('', '', 'no-separator-here')

37. `rsplit()`

Splits the string from the right side, optionally limited by maxsplit.

# Example 1
s = "a,b,c,d"
print(s.rsplit(",", 1))  # Output: ['a,b,c', 'd']

# Example 2
path = "folder/subfolder/file.txt"
print(path.rsplit("/", 1))  # Output: ['folder/subfolder', 'file.txt']

38. `rstrip()`

Removes trailing whitespace (or specified characters) from the string.

# Example 1
s = "hello   "
print(s.rstrip())  # Output: "hello"

# Example 2
s = "hello***"
print(s.rstrip("*"))  # Output: "hello"

39. `split()`

Splits the string into a list using a separator (default: whitespace).

# Example 1
s = "the quick brown fox"
print(s.split())  # Output: ['the', 'quick', 'brown', 'fox']

# Example 2
csv_line = "name,age,city"
print(csv_line.split(","))  # Output: ['name', 'age', 'city']

40. `splitlines()`

Splits the string at line boundaries (\n, \r\n, etc.), returning a list of lines.

# Example 1
text = "line1\nline2\nline3"
print(text.splitlines())  # Output: ['line1', 'line2', 'line3']

# Example 2
text = "line1\nline2"
print(text.splitlines(keepends=True))  # Output: ['line1\n', 'line2']

41. `startswith()`

Checks whether the string starts with the specified prefix (or tuple of prefixes).

# Example 1
url = "https://example.com"
print(url.startswith("https"))  # Output: True

# Example 2
filename = "image.png"
print(filename.startswith(("img", "image", "photo")))  # Output: True

42. `strip()`

Removes leading and trailing whitespace (or specified characters) from the string.

# Example 1
s = "   hello world   "
print(s.strip())  # Output: "hello world"

# Example 2
s = "###title###"
print(s.strip("#"))  # Output: "title"

43. `swapcase()`

Swaps the case of all characters: uppercase becomes lowercase and vice versa.

# Example 1
s = "Hello World"
print(s.swapcase())  # Output: "hELLO wORLD"

# Example 2
s = "PyThOn"
print(s.swapcase())  # Output: "pYtHoN"

44. `title()`

Converts the string to title case (first letter of each word capitalized).

# Example 1
s = "the great gatsby"
print(s.title())  # Output: "The Great Gatsby"

# Example 2
s = "hello world! it's python"
print(s.title())  # Output: "Hello World! It'S Python"

45. `translate()`

Applies a translation table (created via maketrans()) to replace or delete characters.

# Example 1
table = str.maketrans("aeiou", "12345")
print("hello world".translate(table))  # Output: "h2ll4 w4rld"

# Example 2
table = str.maketrans({"a": None, "e": None})  # delete a and e
print("adventure".translate(table))  # Output: "dvntur"

46. `upper()`

Converts all characters in the string to uppercase.

# Example 1
s = "hello world"
print(s.upper())  # Output: "HELLO WORLD"

# Example 2
code = "abc123"
print(code.upper())  # Output: "ABC123"

47. `zfill()`

Pads the string on the left with zeros to fill a specified width (handles sign prefixes correctly).

# Example 1
s = "42"
print(s.zfill(5))  # Output: "00042"

# Example 2
s = "-42"
print(s.zfill(6))  # Output: "-00042"

Quick Reference Table

#	Method	Purpose
1	`capitalize()`	Capitalize first letter
2	`casefold()`	Aggressive lowercase for matching
3	`center()`	Center-align with padding
4	`count()`	Count substring occurrences
5	`encode()`	Convert to bytes
6	`endswith()`	Check suffix
7	`expandtabs()`	Replace tabs with spaces
8	`find()`	Locate substring (returns -1 if missing)
9	`format()`	Template string formatting
10	`format_map()`	Format using a mapping
11	`index()`	Locate substring (raises error if missing)
12	`isalnum()`	Check alphanumeric
13	`isalpha()`	Check alphabetic
14	`isascii()`	Check ASCII-only
15	`isdecimal()`	Check decimal digits
16	`isdigit()`	Check digit characters
17	`isidentifier()`	Check valid identifier
18	`islower()`	Check lowercase
19	`isnumeric()`	Check numeric characters
20	`isprintable()`	Check printable characters
21	`isspace()`	Check whitespace
22	`istitle()`	Check title case
23	`isupper()`	Check uppercase
24	`join()`	Join iterable into string
25	`ljust()`	Left-justify with padding
26	`lower()`	Convert to lowercase
27	`lstrip()`	Strip leading characters
28	`maketrans()`	Build translation table
29	`partition()`	Split into 3 parts at first match
30	`removeprefix()`	Remove leading prefix
31	`removesuffix()`	Remove trailing suffix
32	`replace()`	Replace substring
33	`rfind()`	Locate substring from right
34	`rindex()`	Locate from right (raises error)
35	`rjust()`	Right-justify with padding
36	`rpartition()`	Split into 3 parts at last match
37	`rsplit()`	Split from the right
38	`rstrip()`	Strip trailing characters
39	`split()`	Split into list
40	`splitlines()`	Split at line boundaries
41	`startswith()`	Check prefix
42	`strip()`	Strip leading & trailing characters
43	`swapcase()`	Swap character case
44	`title()`	Convert to title case
45	`translate()`	Apply translation table
46	`upper()`	Convert to uppercase
47	`zfill()`	Zero-pad on the left

Python String Manipulation Functions — Full Reference

1. capitalize()

2. casefold()

3. center()

4. count()

5. encode()

6. endswith()

7. expandtabs()

8. find()

9. format()

10. format_map()

11. index()

12. isalnum()

13. isalpha()

14. isascii()

15. isdecimal()

16. isdigit()

17. isidentifier()

18. islower()

19. isnumeric()

20. isprintable()

21. isspace()

22. istitle()

23. isupper()

24. join()

25. ljust()

26. lower()

27. lstrip()

28. maketrans()

29. partition()

30. removeprefix()

31. removesuffix()

32. replace()

33. rfind()

34. rindex()

35. rjust()

36. rpartition()

37. rsplit()

38. rstrip()

39. split()

40. splitlines()

41. startswith()

42. strip()

43. swapcase()

44. title()

45. translate()

46. upper()

47. zfill()