Identity and Membership Operators

Special Operators

Python language offers some special type of operators like the identity operator or the membership operator. They are described below with examples.

Identity Operators

  • Identity operators are used to compare the memory locations of two objects.
  • 'is' and 'is not' are the identity operators in Python
  • Output will be boolean value ( TRUE or FALSE)
  • Note: For understanding purpose retriving id details (i.e) memory allocation. But in real time you can directly use 'is' operator. No need to verify the memory address.

    # Example 1 - Numbers using 'is' operator
    x = 10
    print("memory location of x is",id(x))
    
    y = 10
    print("memory location of y is",id(y))
    
    print (x is y) #10 is object created once both x and y points to same object
    
    Output:
    memory location of x is 140708939362336
    memory location of y is 140708939362336
    True
    
    # Example 2 - String using 'is' operator
    a = "Python"
    print("memory location of a is",id(a))
    
    b = "Python"
    print("memory location of b is",id(b))
    
    # "Python" is object created once both a and b points to same object
    print (a is b)
    
    Output:
    memory location of a is 2332982898792
    memory location of b is 2332982898792
    True
    
    # Example 3  - List using 'is' operator
    l1 = [1,2,3,4]
    print("memory location of l1 is",id(l1))
    
    l2 = [1,2,3,4]
    print("memory location of l2 is",id(l2))
    
    print (l1 is l2) # list l1 and l1 will create a separate objects 
    
    Output:
    memory location of l1 is 2333051991112
    memory location of l2 is 2333042340296
    False
    
    # Example 4 - Numbers using 'is not' operator
    x = 10
    y = 10
    print (x is not y) 
    
    a = 20 
    b = 15
    
    print(a is not b)
    
    Output:
    False
    True
    
    # Example 5 - String using 'is not' operator
    s1 = "Python"
    s2 = "Python"
    print (s1 is not s2) 
    
    s3 = "Python"
    s4 = "Java"
    print (s3 is not s4) 
    
    Output:
    False
    True
    
    # Example 6  - List using 'is' operator
    l1 = [1,2,3,4]
    l2 = [1,2,3,4]
    print (l1 is not l2) 
    
    Output:
    True
    

    Conclusion:
         'is' operator will display true if the memory address is same and
         'is not' operator will display true if the memory address is different.

    Membership Operators

  • Membership operators are used to verify whether a value or variable is found in a sequence (Eg: string, list, tuple and dictionary)
  • 'in' and 'not in' are the membership operators in Python.
  • Output will be boolean value ( TRUE or FALSE)
  • # Example 1 - List using 'in' operator
    mylist = [1,2.5,"Python",10]
    print(10 in mylist)
    print("Python" in mylist)
    print(5 in mylist)
    
    Output:
    True
    True
    False
    
    # Example 2 - List using 'not in' operator
    mylist2 = [1,12.5,"Java",35]
    print(10 not in mylist2)
    print("Java" not in mylist2)
    
    Output:
    True
    False
    

    Conclusion:
         'in' operator will display true if the value is found in the sequence and
         'not in' operator will display true if the value is not found in the sequence.

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