In Python, a string is a sequence of Unicode characters enclosed within single ('), double ("), or triple quotes (''' or """). Triple quotes are particularly useful for multi-line strings. Strings are immutable, meaning once created, their contents cannot be changed. However, you can create new strings based on existing ones.
# Single-line strings
single = 'Hello'
double = "World"
# Multi-line string
multi = """This is
a multi-line
string."""
You can concatenate strings using the + operator.
greeting = "Hello, " + "World!"
print(greeting) # Output: Hello, World!
Introduced in Python 3.6, formatted string literals (f-strings) allow embedding expressions inside string literals. The syntax is to put an f outside the opening quotation mark of a string and to insert variables into the string wrapped in curly brackets.
name = "Adam"
age = 34
print(f"{name} is {age} years old.") # Output: Adam is 34 years old.
You can include special characters in a string such as quotation marks by preceding them with the escape character \.
You can also use the string method
.format().
It takes parameters as arguments and includes them in a string.
def favourite_song_statement(song, artist):
return "My favourite song is {} by {}.".format(song, artist)
Strings in Python can be though of as a list of characters. Like in JavaScript, Python is zero index, so the first letter in a string will have the index of 0 and the index of the last letter is the length of the string minus 1.
text = "Python"
print(text[0]) # Output: 'P'
print(text[-1]) # Output: 'n'
print(text[len(text)-1]) # Output: 'n'
print(text[1:4]) # Output: 'yth'
The length of a string can be determined using
len().
len(string) # Gives the length of the string
Methods in Python also follow dot notation so will take the syntax of
variable.method(parameter).
lower(): Converts to lowercase.upper(): Converts to uppercase.capitalize(): Capitalises the first character.title(): Capitalizes the first character of each word.swapcase(): Swaps case of each character.count(): Returns the amount of times a specified value occurs.endswith(): Returns True if the string ends with a given suffix.find(sub): Returns the lowest index of substring sub; returns -1 if not found.rfind(sub): Returns the highest index of substring sub; returns -1 if not found.index(sub): Like find(), but raises a ValueError if sub is not found.replace(old, new): Replaces occurrences of old with new.expandstabs(): Sets the tab size in spaces of the string.strip(): Removes leading and trailing whitespace.lstrip(): Removes leading whitespace.rstrip(): Removes trailing whitespace.center(width, fillchar): Centers string in a field of given width, padded with fillchar.ljust(width, fillchar): Left-justifies string.rjust(width, fillchar): Right-justifies string.partition(): Returns a tuple where the string is parted into two strings and the separator.split("delimiter"): Splits string into a list using a given delimiter. By default it uses a space.rpartition(): Returns a tuple where the string is parted into three parts.rsplit(sep): Splits string from the right.splitlines(): Splits string at line breaks.'delimiter'.join(iterable): Joins elements of iterable with a given delimiter.isalnum(): Checks if all characters are alphanumeric.isalpha(): Checks if all characters are alphabetic.isdigit(): Checks if all characters are digits.islower(): Checks if all characters are lowercase.isupper(): Checks if all characters are uppercase.isspace(): Checks if all characters are whitespace.istitle(): Checks if string is titlecased.encode(encoding): Encodes string using specified encoding.decode(encoding): Decodes bytes to string using specified encoding.