Strings in Python

Python provides a rich collection of built-in string functions and methods for manipulating and analyzing text data. These functions are essential tools for text processing in Python applications.

Basic String Functions

• len() - Returns the number of characters in a string
• str() - Converts other data types to string representation
• repr() - Returns a printable representation of an object, often used for debugging

String Case Manipulation

• upper() - Converts all characters to uppercase
• lower() - Converts all characters to lowercase
• capitalize() - Capitalizes the first character of the string
• title() - Converts the first character of each word to uppercase
• swapcase() - Swaps case of each character (lowercase becomes uppercase and vice versa)

String Searching and Validation

• find() - Returns the lowest index of a substring, or -1 if not found
• rfind() - Returns the highest index of a substring, searching from right
• index() - Similar to find() but raises ValueError if substring is not found
• count() - Returns the number of occurrences of a substring
• startswith() - Returns True if string starts with the specified prefix
• endswith() - Returns True if string ends with the specified suffix
• isalpha() - Returns True if all characters are alphabetic
• isdigit() - Returns True if all characters are digits
• isalnum() - Returns True if all characters are alphanumeric
• isspace() - Returns True if all characters are whitespace
• islower() - Returns True if all characters are lowercase
• isupper() - Returns True if all characters are uppercase
• istitle() - Returns True if string is title-cased

String Transformation

• replace() - Replaces occurrences of a substring with another
• strip() - Removes leading and trailing whitespace (or specified characters)
• lstrip() - Removes leading whitespace (or specified characters)
• rstrip() - Removes trailing whitespace (or specified characters)
• split() - Splits string into a list based on a delimiter
• rsplit() - Splits string from the right
• splitlines() - Splits string at line breaks
• join() - Concatenates elements of an iterable with the string as separator
• partition() - Splits the string at the first occurrence of a separator
• rpartition() - Splits the string at the last occurrence of a separator

String Formatting

• format() - Formats string using positional and keyword arguments
• center() - Centers string in a field of specified width
• ljust() - Left-aligns string in a field of specified width
• rjust() - Right-aligns string in a field of specified width
• zfill() - Pads string with zeros on the left
• expandtabs() - Replaces tabs with spaces

String Encoding and Conversion

• encode() - Returns encoded version of the string
• decode() - Decodes the string using the specified encoding
• maketrans() - Creates a translation table for translate()
• translate() - Returns a translated string using a translation table

String Content Inspection

• ord() - Returns the Unicode code point for a character
• chr() - Returns the character for a Unicode code point

String functions in Python are method-based (called on string objects) and provide a consistent, powerful interface for text processing. Understanding these functions enables efficient text analysis, cleaning, and transformation in Python applications.