Python string methods are built-in functions that allow you to manipulate and analyze strings. Since strings in Python are immutable, these methods return a new string rather than modifying the original.

Core String Methods

• Case Manipulation:

  • upper(): Converts all characters to uppercase.

  • lower(): Converts all characters to lowercase.

  • capitalize(): Capitalizes the first character and makes the rest lowercase.

  • title(): Capitalizes the first letter of each word.

  • swapcase(): Swaps the case of all characters.

  • casefold(): More aggressive than lower(); used for caseless matching.

• Search and Find:

  • find(): Returns the index of the first occurrence of a substring (returns -1 if not found).

  • index(): Similar to find(), but raises a ValueError if not found.

  • rfind(): Returns the highest index of a substring.

  • rindex(): Similar to rfind(), but raises an exception if not found.

  • count(): Returns the number of times a substring appears.

• Checking Conditions (Boolean):

  • isalnum(): Returns True if all characters are alphanumeric.

  • isalpha(): Returns True if all characters are alphabetic.

  • isdigit(): Returns True if all characters are digits.

  • isnumeric(): Returns True if all characters are numeric (includes Unicode numerals).

  • isidentifier(): Checks if the string is a valid Python identifier.

  • islower(), isupper(): Check if all characters are lowercase or uppercase.

  • isspace(): Returns True if the string contains only whitespace.

  • istitle(): Returns True if the string is title-cased.

  • isprintable(): Returns True if all characters are printable.

• Trim and Align:

  • strip(): Removes leading and trailing whitespace (or specified characters).

  • lstrip(): Removes leading whitespace.

  • rstrip(): Removes trailing whitespace.

  • center(width, fillchar): Centers the string within a specified width using a fill character.

  • ljust(width, fillchar): Left-aligns the string.

  • rjust(width, fillchar): Right-aligns the string.

  • expandtabs(tabsize): Replaces tab characters with spaces.

• Split and Join:

  • split(sep): Splits the string into a list using a separator (default is whitespace).

  • rsplit(sep): Splits from the right.

  • splitlines(): Splits the string at line boundaries.

  • join(iterable): Joins elements of an iterable into a single string with the string as a separator.

• Replace and Modify:

  • replace(old, new, count): Replaces occurrences of a substring with another.

  • partition(sep): Splits the string into three parts at the first occurrence of a separator.

  • rpartition(sep): Splits at the last occurrence of a separator.

  • removeprefix(prefix): Removes a prefix if present (Python 3.9+).

  • removesuffix(suffix): Removes a suffix if present (Python 3.9+).

• Encoding and Translation:

  • encode(encoding): Encodes the string using the specified encoding.

  • maketrans(x, y, z): Creates a translation table.

  • translate(table): Applies a translation table to the string.

• Starts/Ends With:

  • startswith(prefix): Returns True if the string starts with the given prefix.

  • endswith(suffix): Returns True if the string ends with the given suffix.

• Padding:

  • zfill(width): Pads the string with zeros on the left to fill the specified width.

For full details and examples, refer to the official Python documentation: Built-in Types — Python 3.14.3 documentation.