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10 Python 3 String Methods and Examples with Cheat Sheet

Table of Contents

Python string is a built-in type sequence. Strings can be used to handle textual data in Python. Python Strings are immutable sequences of Unicode points.

There are several built-in Python string methods that allow us to easily make modifications to strings in Python. In this tutorial we will cover the .upper(), .lower(), .count(), .find(), .replace() and str() methods etc.

Python 3 String Methods

  • index() – Searches the string for a specified value and returns the position of where the value is. If the value is a word in a string of sentence, the index will be the number of the first character of the word.
  • istitle() – Returns True if the string follows the rules of a title, which means all words start with an uppercase letter and the rest are lowercase letters.
  • replace() – Replaces the specified value in the string with another specified value in the new string.
  • rfind() – Searches the string for a specified value and returns the last position of where it was found. The index will be the number of the first character of the specified value.
  • rsplit() Splits a string into a list, starting from the right. If no “max” is specified, this method will return the same as the split() method.
  • split() – Splits a string into a list. The default separator is any whitespace, but the separator can be specified (i.e. ,).
  • splitlines() – Uses \n to split the string into a list.
  • strip() – Removes any leading and trailing characters of the specified variables. Unless otherwise specified, the default trailing characters are whitespaces.
  • swapcase() – Swaps all the characters in a string. If the character is an uppercase letter, it’ll turn into a lowercase letter, and vice versa.
  • title() – Converts the first character of each word to uppercase.
  • count() – Returns how many times a character or substring occurs in a string
  • find() – Searches for a specific character or substring. Returns the position of where it was first encountered.

 

Let’s use these test variables:

>>> s = “OH, my paws and whiskers!”
>>> t = “I’m late!”
In the following examples, the Python shell prints the result of the method call, but the original variables s and t are not changed.

Python 3 String Methods – Change Case

>>> s.capitalize()
‘Oh, my paws and whiskers!’
>>> s.lower()
‘oh, my paws and whiskers!’
>>> s.swapcase()
‘oh, MY PAWS AND WHISKERS!’
>>> s.title()
‘Oh, My Paws And Whiskers!’
>>> s.upper()
‘OH, MY PAWS AND WHISKERS!’
Search
>>> s.count(‘w’)
2
>>> s.find(‘w’)
9
>>> s.index(‘w’)
9
>>> s.rfind(‘w’)
16
>>> s.rindex(‘w’)
16
>>> s.startswith(‘OH’)
True

Python 3 String Methods – Modify

>>> ”.join(s)
‘OH, my paws and whiskers!’
>>> ‘ ‘.join(s)
‘O H , m y p a w s a n d w h i s k e r s !’
>>> ‘ ‘.join((s, t))
“OH, my paws and whiskers! I’m late!”
>>> s.lstrip(‘HO’)
‘, my paws and whiskers!’
>>> s.replace(‘H’, ‘MG’)
‘OMG, my paws and whiskers!’
>>> s.rsplit()
[‘OH,’, ‘my’, ‘paws’, ‘and’, ‘whiskers!’]
>>> s.rsplit(‘ ‘, 1)
[‘OH, my paws and’, ‘whiskers!’]
>>> s.split(‘ ‘, 1)
[‘OH,’, ‘my paws and whiskers!’]
>>> s.split(‘ ‘)
[‘OH,’, ‘my’, ‘paws’, ‘and’, ‘whiskers!’]
>>> s.splitlines()
[‘OH, my paws and whiskers!’]
>>> s.strip()
‘OH, my paws and whiskers!’
>>> s.strip(‘s!’)
‘OH, my paws and whisker’

Python 3 String Methods – Format

>>> s.center(30)
‘ OH, my paws and whiskers! ‘
>>> s.expandtabs()
‘OH, my paws and whiskers!’
>>> s.ljust(30)
‘OH, my paws and whiskers! ‘
>>> s.rjust(30)
‘ OH, my paws and whiskers!’
String Type
>>> s.isalnum()
False
>>> s.isalpha()
False
>>> s.isprintable()
True
>>> s.istitle()
False
>>> s.isupper()
False
>>> s.isdecimal()
False
>>> s.isnumeric()
False

Python 3 String Methods

Method Name Method Description
capitalize Converts the first character of a string to upper case
casefold Converts a string to a lowercase string. Supports more conversions than the lower method. Use when localizing or globalizing strings.
center Returns a centered string
count Returns how many times a character or substring occurs in a string
encode Returns an encoded version of a string
endswith Checks if a string ends with the specific character or substring
expandtabs Specifies a tab size for a string and returns it
find Searches for a specific character or substring. Returns the position of where it was first encountered.
format The old-school way to add variables inside of a string. Formats a string by embedding values into it and returning the result
format_map Formats specific values in a string
index Searches for a character or substring in a string. Returns the index at which it was first encountered.
isalnum Checks if all the characters of the string are alphanumeric
isalpha Checks if all the characters of the string are found in the alphabetical
isascii Checks if all the characters of the string are ASCII values
isdecimal Checks if all the characters of the string are decimal numbers
isdigit Checks if all the characters of the string are numeric digits
isidentifier Checks if a string is an identifier
islower Checks if all characters of a string are lower case
isnumeric Checks if all characters of a string are numeric
isprintable Checks if all characters of a string are printable
isspace Checks if all characters of a string are white spaces
istitle Checks if a string follows title capitalization rules (every word begins with a capital letter)
isupper Checks if all characters of a string are upper case
join Joins items of an iterable (such as a list) to the end of a string
ljust Returns a left-justified version of a string
lower Convert a string to lowercase
lstrip Returns a left trim version of a string
maketrans Returns a translation table of a string for translations
partition Breaks a string to parts of three. The desired center part is specified as an argument
removeprefix Removes a prefix from the beginning of a string and returns the string without it.
removesuffix Removes a suffix from the end of a string and returns the string without it.
replace Returns a string where a specific character or substring is replaced with something else
rfind Searches a string for a specific character or substring. Returns the last index at which it was found
rindex Searches a string for a specific character or substring. Returns the last index at which it was found.
rjust Returns a right-justified version of a string
rpartition Breaks a string to parts of three. The desired center part is specified as an argument
rsplit Splits the string at a specific separator, and returns the parts as a list
rstrip Creates and returns a right trim version of a string
split Splits the string at the specified separator, and returns the parts as a list
splitlines Splits a string at line breaks and returns the lines as a list
startswith Checks if a string starts with the specified character or a substring
strip Returns a trimmed version of a string
swapcase Swaps cases. All uppercase characters become lowercases and vice versa
title Converts each word of a string to start with an uppercase letter
translate Returns a translated string
upper Converts a string to upper case
zfill Prefills a string with 0 values
David Cao
David Cao

Hey there! I am David, a Cloud & DevOps Enthusiast and 18 years of experience as a Linux engineer. I work with AWS, Git & GitHub, Linux, Python, Ansible, and Bash. I am a technical blogger and a Software Engineer, enjoy sharing my learning and contributing to open-source.