A String is a data structure in Python Programming that represents a sequence of characters. It is an immutable data type, meaning that once you have created a string, you cannot change it. Python String are used widely in many different applications, such as storing and manipulating text data, representing names, addresses, and other types of data that can be represented as text.
Table of Content
- What is a String in Python?
- Create a String in Python
- Accessing characters in Python String
- String Slicing
- Python String Reversed
- Deleting/Updating from a String
- Escape Sequencing in Python
- Python String Formatting
- Useful Python String Operations
- Python String constants
- Deprecated string functions
- FAQ’s on Python String
What is a String in Python?
Python Programming does not have a character data type, a single character is simply a string with a length of 1. Let’s see the Python string syntax:
Syntax of String Data Type in Python
string_variable = 'Hello, world!'Example of string data type in Python
string_0 = "A Computer Science portal for geeks"print(string_0)print(type(string_0))
Output:
A Computer Science portal for geeks<class 'str'>Create a String in Python
Strings in Python can be created using single quotes or double quotes or even triple quotes.Let us see how we can define a string in Python or how to write string in Python.
Example:
In this example, we will demonstrate different ways to create a Python String. We will create a string using single quotes (‘ ‘), double quotes (” “), and triple double quotes (“”” “””). The triple quotes can be used to declare multiline strings in Python.
# Creating a String# with single QuotesString1 = 'Welcome to the Geeks World'print("String with the use of Single Quotes: ")print(String1)# Creating a String# with double QuotesString1 = "I'm a Geek"print("\nString with the use of Double Quotes: ")print(String1)# Creating a String# with triple QuotesString1 = '''I'm a Geek and I live in a world of "Geeks"'''print("\nString with the use of Triple Quotes: ")print(String1)# Creating String with triple# Quotes allows multiple linesString1 = '''Geeks For Life'''print("\nCreating a multiline String: ")print(String1)
Output:
String with the use of Single Quotes: Welcome to the Geeks WorldString with the use of Double Quotes: I'm a GeekString with the use of Triple Quotes: I'm a Geek and I live in a world of "Geeks"Creating a multiline String: Geeks For LifeAccessing characters in Python String
In Python Programming tutorials, individual characters of a String can be accessed by using the method of Indexing. Indexing allows negative address references to access characters from the back of the String, e.g. -1 refers to the last character, -2 refers to the second last character, and so on.
While accessing an index out of the range will cause an IndexError. Only Integers are allowed to be passed as an index, float or other types that will cause a TypeError.
Python String syntax indexing
Python String Positive Indexing
In this example, we will define a string in Python Programming and access its characters using positive indexing. The 0th element will be the first character of the string.
String1 = "GeeksForGeeks"print("Initial String: ", String1)# Printing First characterprint("First character of String is: ", String1[0])
Output:
Initial String: GeeksForGeeksFirst character of String is: GPython String Negative Indexing
In this example, we will access its characters using negative indexing. The -3th element is the third last character of the string.
String1 = "GeeksForGeeks"print("Initial String: ", String1)# Printing Last characterprint("Last character of String is: ", String1[-3])
Output
Initial String: GeeksForGeeksLast character of String is: eString Slicing Python
In Python Programming tutorials, the String Slicing method is used to access a range of characters in the String. Slicing in a String is done by using a Slicing operator, i.e., a colon (:). One thing to keep in mind while using this method is that the string returned after slicing includes the character at the start index but not the character at the last index.
In this example, we will use the string-slicing method to extract a substring of the original string. The [3:12] indicates that the string slicing will start from the 3rd index of the string to the 12th index, (12th character not including). We can also use negative indexing in string slicing.
# Creating a StringString1 = "GeeksForGeeks"print("Initial String: ")print(String1)# Printing 3rd to 12th characterprint("\nSlicing characters from 3-12: ")print(String1[3:12])# Printing characters between# 3rd and 2nd last characterprint("\nSlicing characters between " + "3rd and 2nd last character: ")print(String1[3:-2])
Output:
Initial String: GeeksForGeeksSlicing characters from 3-12: ksForGeekSlicing characters between 3rd and 2nd last character: ksForGeePython String Reversed
In Python Programming tutorials, By accessing characters from a string, we can also reverse strings in Python Programming. We can Reverse a string by using String slicing method.
In this example, we will reverse a string by accessing the index. We did not specify the first two parts of the slice indicating that we are considering the whole string, from the start index to the last index.
#Program to reverse a stringgfg = "geeksforgeeks"print(gfg[::-1])
Output:
skeegrofskeegBuildIn Reverse Function in Python
We can also reverse a string by using built-in join and reversed functions, and passing the string as the parameter to the reversed() function.
# Program to reverse a stringgfg = "geeksforgeeks"# Reverse the string using reversed and join functiongfg = "".join(reversed(gfg))print(gfg)
Output:
skeegrofskeegDeleting/Updating from a String
In Python, the Updation or deletion of characters from a String is not allowed. This will cause an error because item assignment or item deletion from a String is not supported. Although deletion of the entire String is possible with the use of a built-in del keyword. This is because Strings are immutable, hence elements of a String cannot be changed once assigned. Only new strings can be reassigned to the same name.
Updating a character
A character of a string can be updated in Python by first converting the string into a Python List and then updating the element in the list. As lists are mutable in nature, we can update the character and then convert the list back into the String.
Another method is using the string slicing method. Slice the string before the character you want to update, then add the new character and finally add the other part of the string again by string slicing.
Example:
In this example, we are using both the list and the string slicing method to update a character. We converted the String1 to a list, changes its value at a particular element, and then converted it back to a string using the Python string join() method.
In the string-slicing method, we sliced the string up to the character we want to update, concatenated the new character, and finally concatenate the remaining part of the string.
# Python Program to Update# character of a StringString1 = "Hello, I'm a Geek"print("Initial String: ")print(String1)# Updating a character of the String## As python strings are immutable, they don't support item updation directly### there are following two ways#1list1 = list(String1)list1[2] = 'p'String2 = ''.join(list1)print("\nUpdating character at 2nd Index: ")print(String2)#2String3 = String1[0:2] + 'p' + String1[3:]print(String3)
Output:
Initial String:Hello, I'm a GeekUpdating character at 2nd Index:Heplo, I'm a GeekHeplo, I'm a GeekUpdating Entire String
In Python Programming, As Python strings are immutable in nature, we cannot update the existing string. We can only assign a completely new value to the variable with the same name.
Example: In this example, we first assign a value to ‘String1’ and then updated it by assigning a completely different value to it. We simply changed its reference.
# Python Program to Update# entire StringString1 = "Hello, I'm a Geek"print("Initial String: ")print(String1)# Updating a StringString1 = "Welcome to the Geek World"print("\nUpdated String: ")print(String1)
Output:
Initial String: Hello, I'm a GeekUpdated String: Welcome to the Geek World Deleting a character
Python strings are immutable, that means we cannot delete a character from it. When we try to delete thecharacter using the del keyword, it will generate an error.
# Python Program to delete# character of a StringString1 = "Hello, I'm a Geek"print("Initial String: ")print(String1)print("Deleting character at 2nd Index:")del String1[2]print(String1)
Output:
Initial String: Hello, I'm a GeekDeleting character at 2nd Index: Traceback (most recent call last): File "e:\GFG\Python codes\Codes\demo.py", line 9, in <module> del String1[2]TypeError: 'str' object doesn't support item deletionBut using slicing we can remove the character from the original string and store the result in a new string.
Example: In this example, we will first slice the string up to the character that we want to delete and then concatenate the remaining string next from the deleted character.
# Python Program to Delete# characters from a StringString1 = "Hello, I'm a Geek"print("Initial String: ")print(String1)# Deleting a character# of the StringString2 = String1[0:2] + String1[3:]print("\nDeleting character at 2nd Index: ")print(String2)
Output:
Initial String:Hello, I'm a GeekDeleting character at 2nd Index:Helo, I'm a GeekDeleting Entire String
In Python Programming, Deletion of the entire string is possible with the use of del keyword. Further, if we try to print the string, this will produce an error because the String is deleted and is unavailable to be printed.
# Python Program to Delete# entire StringString1 = "Hello, I'm a Geek"print("Initial String: ")print(String1)# Deleting a String# with the use of deldel String1print("\nDeleting entire String: ")print(String1)
Error:
Traceback (most recent call last):File "/home/e4b8f2170f140da99d2fe57d9d8c6a94.py", line 12, inprint(String1)NameError: name 'String1' is not defined Escape Sequencing in Python
While printing Strings with single and double quotes in it causes SyntaxError because String already contains Single and Double Quotes and hence cannot be printed with the use of either of these. Hence, to print such a String either Triple Quotes are used or Escape sequences are used to print Strings.
Escape sequences start with a backslash and can be interpreted differently. If single quotes are used to represent a string, then all the single quotes present in the string must be escaped and the same is done for Double Quotes.
# Initial StringString1 = '''I'm a "Geek"'''print("Initial String with use of Triple Quotes: ")print(String1)# Escaping Single QuoteString1 = 'I\'m a "Geek"'print("\nEscaping Single Quote: ")print(String1)# Escaping Double QuotesString1 = "I'm a \"Geek\""print("\nEscaping Double Quotes: ")print(String1)# Printing Paths with the# use of Escape SequencesString1 = "C:\\Python\\Geeks\\"print("\nEscaping Backslashes: ")print(String1)# Printing Paths with the# use of TabString1 = "Hi\tGeeks"print("\nTab: ")print(String1)# Printing Paths with the# use of New LineString1 = "Python\nGeeks"print("\nNew Line: ")print(String1)
Output:
Initial String with use of Triple Quotes: I'm a "Geek"Escaping Single Quote: I'm a "Geek"Escaping Double Quotes: I'm a "Geek"Escaping Backslashes: C:\Python\Geeks\Tab: Hi GeeksNew Line: PythonGeeksExample:
To ignore the escape sequences in a String, r or R is used, this implies that the string is a raw string and escape sequences inside it are to be ignored.
# Printing hello in octalString1 = "\110\145\154\154\157"print("\nPrinting in Octal with the use of Escape Sequences: ")print(String1)# Using raw String to# ignore Escape SequencesString1 = r"This is \110\145\154\154\157"print("\nPrinting Raw String in Octal Format: ")print(String1)# Printing Geeks in HEXString1 = "This is \x47\x65\x65\x6b\x73 in \x48\x45\x58"print("\nPrinting in HEX with the use of Escape Sequences: ")print(String1)# Using raw String to# ignore Escape SequencesString1 = r"This is \x47\x65\x65\x6b\x73 in \x48\x45\x58"print("\nPrinting Raw String in HEX Format: ")print(String1)
Output:
Printing in Octal with the use of Escape Sequences: HelloPrinting Raw String in Octal Format: This is \110\145\154\154\157Printing in HEX with the use of Escape Sequences: This is Geeks in HEXPrinting Raw String in HEX Format: This is \x47\x65\x65\x6b\x73 in \x48\x45\x58Python String Formatting
Strings in Python or string data type in Python can be formatted with the use of format() method which is a very versatile and powerful tool for formatting Strings. Format method in String contains curly braces {} as placeholders which can hold arguments according to position or keyword to specify the order.
Example 1: In this example, we will declare a string which contains the curly braces {} that acts as a placeholders and provide them values to see how string declaration position matters.
# Python Program for# Formatting of Strings# Default orderString1 = "{} {} {}".format('Geeks', 'For', 'Life')print("Print String in default order: ")print(String1)# Positional FormattingString1 = "{1} {0} {2}".format('Geeks', 'For', 'Life')print("\nPrint String in Positional order: ")print(String1)# Keyword FormattingString1 = "{l} {f} {g}".format(g='Geeks', f='For', l='Life')print("\nPrint String in order of Keywords: ")print(String1)
Output:
Print String in default order: Geeks For LifePrint String in Positional order: For Geeks LifePrint String in order of Keywords: Life For GeeksExample 2: Integers such as Binary, hexadecimal, etc., and floats can be rounded or displayed in the exponent form with the use of format specifiers.
# Formatting of IntegersString1 = "{0:b}".format(16)print("\nBinary representation of 16 is ")print(String1)# Formatting of FloatsString1 = "{0:e}".format(165.6458)print("\nExponent representation of 165.6458 is ")print(String1)# Rounding off IntegersString1 = "{0:.2f}".format(1/6)print("\none-sixth is : ")print(String1)
Output:
Binary representation of 16 is 10000Exponent representation of 165.6458 is 1.656458e+02one-sixth is : 0.17Example 3: In String data type in Python , A string can be left, right, or center aligned with the use of format specifiers, separated by a colon(:).The (<) indicates that the string should be aligned to the left, (>) indicates that the string should be aligned to the right and (^) indicates that the string should be aligned to the center. We can also specify the length in which it should be aligned. For example, (<10) means that the string should be aligned to the left within a field of width of 10 characters.
# String alignmentString1 = "|{:<10}|{:^10}|{:>10}|".format('Geeks', 'for', 'Geeks')print("\nLeft, center and right alignment with Formatting: ")print(String1)# To demonstrate aligning of spacesString1 = "\n{0:^16} was founded in {1:<4}!".format("GeeksforGeeks", 2009)print(String1)
Output:
Left, center and right alignment with Formatting: |Geeks | for | Geeks| GeeksforGeeks was founded in 2009 !Example 4: Old-style formatting was done without the use of the format method by using the % operator
# Python Program for# Old Style Formatting# of IntegersInteger1 = 12.3456789print("Formatting in 3.2f format: ")print('The value of Integer1 is %3.2f' % Integer1)print("\nFormatting in 3.4f format: ")print('The value of Integer1 is %3.4f' % Integer1)
Output:
Formatting in 3.2f format: The value of Integer1 is 12.35Formatting in 3.4f format: The value of Integer1 is 12.3457Similar Reads – String Methods
Useful Python String Operations
- Logical Operators on String
- String Formatting using %
- String Template Class
- Split a string
- Python Docstrings
- String slicing
- Find all duplicate characters in string
- Reverse string in Python (5 different ways)
- Python program to check if a string is palindrome or not
Python String constants
Built-In Function | Description |
|---|---|
| string.ascii_letters | Concatenation of the ascii_lowercase and ascii_uppercase constants. |
| string.ascii_lowercase | Concatenation of lowercase letters |
| string.ascii_uppercase | Concatenation of uppercase letters |
| string.digits | Digit in strings |
| string.hexdigits | Hexadigit in strings |
string.letters | concatenation of the strings lowercase and uppercase |
string.lowercase | A string must contain lowercase letters. |
string.octdigits | Octadigit in a string |
string.punctuation | ASCII characters having punctuation characters. |
string.printable | String of characters which are printable |
| String.endswith() | Returns True if a string ends with the given suffix otherwise returns False |
| String.startswith() | Returns True if a string starts with the given prefix otherwise returns False |
| String.isdigit() | Returns “True” if all characters in the string are digits, Otherwise, It returns “False”. |
| String.isalpha() | Returns “True” if all characters in the string are alphabets, Otherwise, It returns “False”. |
| string.isdecimal() | Returns true if all characters in a string are decimal. |
| str.format() | one of the string formatting methods in Python3, which allows multiple substitutions and value formatting. |
| String.index | Returns the position of the first occurrence of substring in a string |
string.uppercase | A string must contain uppercase letters. |
| string.whitespace | A string containing all characters that are considered whitespace. |
| string.swapcase() | Method converts all uppercase characters to lowercase and vice versa of the given string, and returns it |
| replace() | returns a copy of the string where all occurrences of a substring is replaced with another substring. |
Deprecated string functions
Built-In Function | Description |
|---|---|
| string.Isdecimal | Returns true if all characters in a string are decimal |
| String.Isalnum | Returns true if all the characters in a given string are alphanumeric. |
| string.Istitle | Returns True if the string is a title cased string |
| String.partition | splits the string at the first occurrence of the separator and returns a tuple. |
| String.Isidentifier | Check whether a string is a valid identifier or not. |
| String.len | Returns the length of the string. |
| String.rindex | Returns the highest index of the substring inside the string if substring is found. |
| String.Max | Returns the highest alphabetical character in a string. |
| String.min | Returns the minimum alphabetical character in a string. |
| String.splitlines | Returns a list of lines in the string. |
| string.capitalize | Return a word with its first character capitalized. |
| string.expandtabs | Expand tabs in a string replacing them by one or more spaces |
| string.find | Return the lowest indexing a sub string. |
| string.rfind | find the highest index. |
| string.count | Return the number of (non-overlapping) occurrences of substring sub in string |
| string.lower | Return a copy of s, but with upper case, letters converted to lower case. |
| string.split | Return a list of the words of the string, If the optional second argument sep is absent or None |
| string.rsplit() | Return a list of the words of the string s, scanning s from the end. |
| rpartition() | Method splits the given string into three parts |
string.splitfields | Return a list of the words of the string when only used with two arguments. |
| string.join | Concatenate a list or tuple of words with intervening occurrences of sep. |
| string.strip() | It returns a copy of the string with both leading and trailing white spaces removed |
| string.lstrip | Return a copy of the string with leading white spaces removed. |
| string.rstrip | Return a copy of the string with trailing white spaces removed. |
| string.swapcase | Converts lower case letters to upper case and vice versa. |
| string.translate | Translate the characters using table |
| string.upper | lower case letters converted to upper case. |
| string.ljust | left-justify in a field of given width. |
| string.rjust | Right-justify in a field of given width. |
| string.center() | Center-justify in a field of given width. |
| string-zfill | Pad a numeric string on the left with zero digits until the given width is reached. |
| string.replace | Return a copy of string s with all occurrences of substring old replaced by new. |
| string.casefold() | Returns the string in lowercase which can be used for caseless comparisons. |
| string.encode | Encodes the string into any encoding supported by Python. The default encoding is utf-8. |
| string.maketrans | Returns a translation table usable for str.translate() |
Use of String in Python
- Strings are extensively used for text processing tasks such as searching, extracting, modifying, and formatting text data.
- Strings are used to read input from users via the standard input (stdin) or command-line arguments and to display output using print statements.
- Strings are used to represent data in various formats, including JSON, XML, CSV, and more. They are often manipulated to extract specific information or transform data structures.
- Strings are used to read from and write to text files. They facilitate operations such as reading the contents of a file, writing data to a file, and manipulating file paths.
- Strings support a wide range of operations such as concatenation, slicing, indexing, searching, replacing, and splitting. These operations enable developers to manipulate and transform text efficiently.
Advantages of String in Python:
- Strings are used at a larger scale i.e. for a wide areas of operations such as storing and manipulating text data, representing names, addresses, and other types of data that can be represented as text.
- Python has a rich set of string methods that allow you to manipulate and work with strings in a variety of ways. These methods make it easy to perform common tasks such as converting strings to uppercase or lowercase, replacing substrings, and splitting strings into lists.
- Strings are immutable, meaning that once you have created a string, you cannot change it. This can be beneficial in certain situations because it means that you can be confident that the value of a string will not change unexpectedly.
- Python has built-in support for strings, which means that you do not need to import any additional libraries or modules to work with strings. This makes it easy to get started with strings and reduces the complexity of your code.
- Python has a concise syntax for creating and manipulating strings, which makes it easy to write and read code that works with strings.
Drawbacks of String in Python:
- When we are dealing with large text data, strings can be inefficient. For instance, if you need to perform a large number of operations on a string, such as replacing substrings or splitting the string into multiple substrings, it can be slow and consume a lot resources.
- Strings can be difficult to work with when you need to represent complex data structures, such as lists or dictionaries. In these cases, it may be more efficient to use a different data type, such as a list or a dictionary, to represent the data.
FAQ’s on Python String
Q.What is a Python string?
A Python string is a sequence of characters enclosed within quotes. It is immutable datatype, its value cannot be altered after it has been created.
Q.How can I create a string in Python?
Strings can be created using single quotes, double quotes, or triple quotes. For Example:
Single quotes: ‘Hii’
Double quotes: “Geeks”
Triple quotes: ”’Welcome”’ “””Greeks”””
Q.How can I access characters in a string?
Python strings are zero-indexed, so we can access single character using indexing. For Example:
String = “GeeksForGeeks”
Print(String[0]) ‘ Output= G ‘
Print(String[-1]) ‘ Output= s ‘
Q.Can I concatenate strings in Python?
Yes, you can concatenate strings using the ‘+’ operator. For Example:
first_name = “Raja”
last_name = “Ram”
full_name = first_name + ” ” + last_name
Q.How can I get the length of a string?
The length of a string can be obtained using the ‘len()’ function. For Example:
string = “GeeksForGeeks”
length = len(string)
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