Working with Strings in Python 3
Last Updated :
31 Jul, 2023
In Python, sequences of characters are referred to as Strings. It used in Python to record text information, such as names. Python strings are “immutable” which means they cannot be changed after they are created.
Creating a String
Strings can be created using single quotes, double quotes, or even triple quotes. Python treats single quotes the same as double-quotes.
Python3
String = 'Hello Geek'
print("Creating string with single quotes :", String)
String = "yes, I am Geek"
print("Creating String with double quotes :", String)
String =
print("Creating String with triple quotes :", String)
|
Output
Creating string with single quotes : Hello Geek
Creating String with double quotes : yes, I am Geek
Creating String with triple quotes : yes, I am Geek
Note: Be careful with quotes!
Python3
String = 'Yes' I am geek'
print(String)
|
Output
File "<ipython-input-10-794636cfedda>", line 3
String = 'Yes' I am geek'
^
SyntaxError: invalid syntax
The reason for the error above is the single quote in Yes’ I stopped the string. If you want to print ‘WithQuotes’ in python, this can’t be done with only single (or double) quotes alone, it requires simultaneous use of both. The best way to avoid this error use double-quotes.
Example:
Python3
print("'WithQuotes'")
print("Hello 'Python'")
print('"WithQuotes"')
print('Hello "Python"')
|
Output
'WithQuotes'
Hello 'Python'
"WithQuotes"
Hello "Python"
Note: For more information, refer Single and Double Quotes | Python
String Indexing
Strings are a sequence of characters, which means Python can use indexes to call parts of the sequence. There are two ways of indexing.
- Positive Indexing
- Negative Indexing
Positive indexing
Python3
String = "GEEK"
print("The 1st element is : ", String[0])
print("The 2nd element is : ", String[1])
print("The 3rd element is : ", String[2])
print("The 4th element is : ", String[3])
|
Output
The 1st element is : G
The 2nd element is : E
The 3rd element is : E
The 4th element is : K
Negative indexing
Python3
String = "GEEK"
print("The 4th element is : ", String[-1])
print("The 3rd element is : ", String[-2])
print("The 2nd element is : ", String[-3])
print("The 1th element is : ", String[-4])
|
Output
The 4th element is : K
The 3rd element is : E
The 2nd element is : E
The 1th element is : G
Updating Strings
In Python, 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. Python can allow you to reassign a new string to an existing one string.
Python3
String = "Geeks"
String[0] = "Hi!, Geeks"
|
Output
Traceback (most recent call last): File “/home/b298782a4e04df4950426bf4bd5bee99.py”, line 5, in <module> String[0] = “Hi!, Geeks” TypeError: ‘str’ object does not support item assignment
Updating the entire String
Python3
String = "Hello Geeks"
print("Before updating : ", String)
String = "Geeksforgeeks"
print("After updating : ", String)
String = 'Hello World!'
print("Updated String :- ", String[:6] + 'Python')
|
Output
Before updating : Hello Geeks
After updating : Geeksforgeeks
Updated String :- Hello Python
String Slicing
Python slicing is about obtaining a sub-string from the given string by slicing it respectively from start to end.
Python slicing can be done in two ways.
- slice() Constructor
- Extending Indexing
Python3
String = "Geekforgeeks"
s1 = slice(3)
print(String[s1])
print(String[:6])
print(String[1:7])
|
Slicing with negative Index.
Python3
String = "Geekforgeeks"
s1 = slice(-1)
print(String[s1])
print(String[0:-3])
|
Output
Geekforgeek
Geekforge
We can use [ : : ] for specifying the frequency to print elements. It specifies the step after which every element will be printed starting from the given index. If nothing is given then it starts from the 0th index.
Python3
String = "Geekforgeeks"
print(String[::1])
print(String[2::2])
print(String[::-1])
|
Output
Geekforgeeks
efrek
skeegrofkeeG
Note: For more information, refer String Slicing in Python
String Formatting
str.format() and f-strings methods are used to add formatted objects to printed string statements. The string format() method formats the given string. It allows for multiple substitutions and value formatting.
Python3
String = 'Geeksforgeeks'
print("{}, A computer science portal for geeks."
.format(String))
String = 'Geeks'
print("Hello {}, How are you ?".format(String))
val = 2
print("I want {} Burgers! ".format(val))
|
Output
Geeksforgeeks, A computer science portal for geeks.
Hello Geeks, How are you ?
I want 2 Burgers!
Note: For more information, refer Python | format() function
Formatted f-string literals are prefixed with ‘f’ and curly braces { } containing expressions that will be replaced with their values.
Python3
String = 'GeekForGeeks'
print(f"{String}: A Computer Science portal for geeks")
String = 'Geek'
print(f"Yes, I am {String}")
bags = 3
book_in_bag = 12
print(f'There are total {bags * book_in_bag} books')
Dic = {'Portal': 'Geeksforgeeks', 'for': 'Geeks'}
print(f"{Dic['Portal']} is a computer science portal for {Dic['for']}")
|
Output
GeekForGeeks: A Computer Science portal for geeks
Yes, I am Geek
There are total 36 books
Geeksforgeeks is a computer science portal for Geeks
Note: For more information, refer f-strings in Python 3 – Formatted string literals
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