String Data type in Python

In this blog, we will study about strings in Python. String is a built in datatype which is a sequence of characters.

#Create a string
mystring="DataScience"
print(mystring) 
#Here, DataScience is a string


#String can contain a single or multiple characters.
mystring1= 'I love Data Science' 
print(mystring)

#To check the datatype of any variable, we can use the type function.
mystring="DataScience"
print(type(mystring)) 

#O/t- <class 'str'> 
#str means string data type

String can contain alphabets, special characters and numerics also. Further, whenever we provide any input to Python, it is by default taken as a string.

#Can contain any numerics
mystring1="DataScience100"
print(type(mystring1))
#O/t - <class 'str'>


#Can contain any special character
mystring2="DataScience100@gmail.com"
print(type(mystring2))
#O/t - <class 'str'>


#only numerics within a single quote can also be treated as a string
mystring3='1234'
print(type(mystring3))
#O/t - <class 'str'>


#without a quote, it will be an integer
mystring4=1234
print(type(mystring4))


#O/t -<class 'int'>

Let’s discuss about

1. String Initialization
2. Accessing String
3. Editing a String
4. Deleting a String
5. Operators can be applied on String
6. Functions can be performed on String

String Initialization:

Strings can be initialized within either single quotes (‘’), double quotes (“ “), or triple quotes (‘’’ ‘’’ or “”” “””).

#Examples - how to intialize a string
mystring= 'I love Data Science'
print(mystring)

mystring= "I love Data Science"
print(mystring)

mystring= '''I love Data Science'''
print(mystring)

mystring= """I love Data Science"""
print(mystring)

Accessing String:

1. Indexing: String can be accessed by Positive indexing or negative indexing. Ineding refers to the positioning of any characters in a word. As Python follows zero based indexing, the first character starts with positive indexing. However, negative indexing starts with -1.

#Indexing
#Positive Indexing/Zero based Indexing
mystring="Python"
mystring[0]
#O/t- P
#P-0, y-1, t=2, h-3, o-4, n-5


#Negative Indexing
mystring[-3]
#O/t- h

2. Slicing: Slicing is a technique used to extract a portion of a string by specifying a range of indices. It can be done wither by positive indexing or negative indexing.

#1. Basic Slicing #syntax[start index:end index]
mystring="Python"
mystring[1:4]
#O/t- yth


#Omitting the end
mystring[1:]
#O/t- ython


#Omitting the start
mystring[:5]
#O/t- Python


#Slicing with a step
mystring[::2]
#O/t- Pto


#Slicing using Negative indexing
mystring[-4:-1]
tho


#Negative Slicing with a step size
mystring[:-3:3]
P


#Reverse a string using negative indexing
mystring[-1:-7:-1]
nohtyP


#Reverse the whole string
mystring[::-1]
nohtyP evoL

The advantage of using negative indexing is that you can access the string from the end even without knowing its length.

Editing a String:

String is immutable i.e. once it is created it cannot be edited.

#Immutability- a string can never be edited
#Editing a String
str1="I love Python"
str1[0]='u'
print(str1)
#This will show an error - TypeError: 'str' object does not support item assignment

Deleting of a String:

A string can not be edited but it can be deleted using del keyword.

#Deleting a String
print(str1)
del str1
print(str1)

Operators on String:

Arithmetic operators (Additional and multiplication only), Relational Operators, and Membership operators can be applied on a string.

#Arithmetic Operator- +, *
mystring1="I love"
mystring2="Python"
print(mystring1 + mystring2) #This will concatenate the String
print(mystring1*3) #This will print the string 3 times

I lovePython
I loveI loveI love

#Relational Operators 
#Every Relational Operators works on string based on ASCII value
str1="Love"
str2="Python"
print(str1<str2)


#Membership Operator- in, not in

a=['apple', 'banana', 'jack fruit', 'grapes']
if 'apple' not in a:
   print("apple is a member")
else:
  print("not a member")

#O/t- apple is a member

Functions on String

#len() - It provides the length of a string
str1= "I love Python"
len(str1)
#O/t- 13



#max()- It compares the ASCII value of the first character of strings 
a=['apple', 'banana', 'jack fruit', 'grapes']
print(max(a))

#O/t- jack fruit 
#ASCII value of j is greater than the ASCII value of first characters of other words


#min()
print(min(a))

#O/t- apple



#sorted() #To Sort the characters alphabetically
str1='PYTHON'
print(sorted(str1))

#O/t- ['H', 'N', 'O', 'P', 'T', 'Y']



#capitalize() #To capitalize the first letter of every sentence
str1="i love python"
print(str1.capitalize())

#O/t- I love python



#title() #To capitalize the first character of every word
str1="i love python"
print(str1.title())

#O/t- I Love Python



#upper() # To change the characters into uppercase
str1="i love python"
print(str1.upper())

#O/t- I LOVE PYTHON



#lower() # To change the characters into lowercase
str2="I LOVE PYThon"
print(str2.lower())

#O/t- i love python



#swapcase()
str1="I love pytHON"
print(str1.swapcase())

#O/t- i LOVE PYThon



#count - To count how many times a specific word or character appears in a sentence
str1="I love love Python"
print(str1.count("love"))

#O/t- 2



#find- gives the index position of any given word
str1="I love Python"
print(str1.find("Python"))

#O/t- 7



#startswith - To check whether the string starts with the given set of characters
str1= "I love Python"
print(str1. startswith("I love"))

#O/t- True


#endswith- To check whether the string ends with the given set of characters
str1= "I love Python"
print(str1.endswith("python"))

#O/t- False


#isalnum()- To check whether the string contains alphabet or numeric digits
str1= "100"
print(str1.isalnum())

#O/t- True


#isdigit() - To check whether the string contains only numeric digits
str1= "1009937986327845237"
print(str1.isdigit())

#O/t- True



#split() - To split any sentence based on any given delimeter
str1= "I, love/ Python so, much"
print(str1.split(' '))

#O/t- ['I,', 'love/', 'Python', 'so,', 'much']



#join() #To join a set of words based on delimeters
str1=['I ', 'love', 'DataScience']
sentence= '0'.join(str1)
print(sentence)

#O/t- I 0love0DataScience



#replace #To replace any desired word by another word
str1="I love Python"
print(str1.replace("I", "He"))
print(str1)

#O/t- He love Python



#strip - To delete the spaces at the beginning and at the end of any sentence
str1= "       I     love    Python       "
print(str1.strip())

#O/t- I     love    Python

We have discussed everything related to a string. There are many other functions also which can be applied on strings.

Free explanation of String in my channel.

Download the code from my github link- https://colab.research.google.com/drive/1W7R73X5ORdmeAg6FqxF2SheeCiu4t_JN