Strings in Python
Strings in Python
Strings in Python are collection of words enclosed in single quotation marks or double quotation marks. Python does not have a character type to store single characters. A character in Python is a string of length 1.
Creating Strings in Python
Strings in Python are created by enclosing them within single quotation marks, double quotation makrs and even triple quotation marks.
# Python program to exemplify string creation # Creating a string with single quotation marks string1='Welcome to Studyexperts!' print(string1) # Creating a string with double quotation marks string2="Welcome to Studyexperts!" print(string2) # Creating a string with triple quotation marks string3='''Welcome to Studyexperts!''' print(string3) # Creating a string with triple quotation marks # triple quotation marks allow creation of multi-line string string4='''Welcome to Studyexperts!''' print(string4)
Output:
Welcome to Studyexperts! Welcome to Studyexperts! Welcome to Studyexperts! Welcome to Studyexperts!
Accessing Characters of Strings in Python
In Python, individual characters of a string are accessed or acquired by the technique of indexing which makes use of both the positive and negative address references. Negative indexing starts from -1 and returns the first character of the string from the end. Positive indexing starts from 0 and returns the first character of the string from the beginning. Indexing a string may also lead to some errors like IndexError or TypeError which occurs when accessing an index out of range and passing anything but integers as an index respectively.
# Python program to exemplify character access of a string
var_string="Welcome to StudyExperts!"
print("The String is ",var_string)
# Displaying first character
print("First character of the string is ",var_string[0])
# Displaying last character
print("Last character of the string is ",var_string[-1])
Output:
The String is Welcome to StudyExperts! First character of the string is W Last character of the string is !
String Slicing
String slicing is done when a group of characters of s string is need to be obtained and is done using the slicing operator colon (:).
# Python program to exemplify string slicing
var_string="Welcome to StudyExperts!"
print("The String is ",var_string)
# Displaying characters between indexes 3 and 15
print("Characters of the string between indexes 3 and 15 is ",var_string[3:15])
# Displaying characters between indexes 3 and -5
print("Characters of the string between indexes 3 and -5 is ",var_string[3:-5])
Output:
The String is Welcome to StudyExperts! Characters of the string between indexes 3 and 15 is come to Stud Characters of the string between indexes 3 and -5 is come to StudyExp
Deleting/Updating a String
In Python, string data type are immutable which means characters of a string cannot be updated or deleted. Though entire string can be deleted using a built-in keyword del and an already created string variable can be assigned a new string object.
Updating a character:
# Python program to exemplify updating a single character of a string
var_string="Welcome to StudyExperts!"
print("The String is ",var_string)
# Updating a character at index 2
var_string[2]="s"
print("The String after updating a single character is ",var_string)
Output:
The String is Welcome to StudyExperts!
Traceback (most recent call last):
File "main.py", line 7, in <module>
var_string[2]="s"
TypeError: 'str' object does not support item assignment
Updating entire string:
# Python program to exemplify updating string
var_string="Welcome to StudyExperts!"
print("The String is ",var_string)
# Updating entire string
var_string="s"
print("Updated string is ",var_string)
Output:
The String is Welcome to StudyExperts! Updated string is s
Deleting a character:
# Python program to exemplify deleting a character from a string
var_string="Welcome to StudyExperts!"
print("The String is ",var_string)
# deleting a character at index 4
del var_string[4]
print("Updated string is ",var_string)
Output:
The String is Welcome to StudyExperts!
Traceback (most recent call last):
File "main.py", line 7, in <module>
del var_string[4]
TypeError: 'str' object doesn't support item deletion
Deleting entire string:
Trying to display the string after deleting it using the del keyword will result in an error because the string no longer exists.
# Python program to exemplify deleting entire string
var_string="Welcome to StudyExperts!"
print("The String is ",var_string)
# deleting entire string
del var_string
Output:
The String is Welcome to StudyExperts!
Escape Sequencing in Python
Escape sequences are special characters used inside a string so that they can be executed and not ignored as a string. They start with a backslash. If a string is made using single quotation marks, then any single quotation mark of a string to be interpreted as a string should be escaped with a backslash character. To ignore escape sequences in a string, it is preceded by a r or R and is made a raw string.
# Python program to exemplify escape sequencing in Python
var_string="I\"m at StudyExperts!"
print("The String is ",var_string)
var_string="I'm at StudyExperts!"
print("The String is ",var_string)
Output:
The String is I"m at StudyExperts! The String is I'm at StudyExperts!
Formatting of Strings in Python
In Python, strings are formatted using a method called format() which works with sets of curly braces {} that act as placeholders to hold arguments according to position or keyword that specify the order.
# Python program to exemplify string formatting in Python
# Default order of string formatting
var_string="{} {} {}".format("You're","at","StudyExperts!")
print(var_string)
# Positional formatting of string
var_string="{1} {0} {2}".format("at","You're","StudyExperts!")
print(var_string)
# Keyword formatting of string
var_string="{a} {b} {c}".format(b="at",a="You're",c="StudyExperts!")
print(var_string)
Output:
You're at StudyExperts! You're at StudyExperts! You're at StudyExperts!
Integers such as binary, octal, etc., and floats can be approximated or displayed in their exponential form using this method.
var_string="{}".format(56)
print("Binary representation of 56 is: ",end="")
print(var_string)
var_string="{0:e}".format(34.567)
print("Exponent representation of 34.567 is: ",end="")
print(var_string)
var_string="{0:.2f}".format(1/7)
print("1/7 with 2 precision is: ",end="")
print(var_string)
Output:
Binary representation of 56 is: 56 Exponent representation of 34.567 is: 3.456700e+01 1/7 with 2 precision is: 0.14
len() Method
This method is used to find the number of characters a string is made up of.
# Python program to exemplify len() method var_string="StudyExperts" length=len(var_string) print(var_string," is of length ",length)
Output:
StudyExperts is of length 12
String Concatenation
Two or more strings can be concatenated using the concatenation operator “+”. Concatenation of strings do not result in modification of any string but a new string since strings in Python are immutable.
# Python program to exemplify string concatenation var1="Study" var2="Experts" var_string=var1+var2 print(var1) print(var2) print(var_string)
Output:
Study Experts StudyExperts
