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id() function in Python

Last Updated : 29 Nov, 2023
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In Python, id() function is a built-in function that returns the unique identifier of an object. The identifier is an integer, which represents the memory address of the object. The id() function is commonly used to check if two variables or objects refer to the same memory location.

Python id() Function Syntax

Syntax: id(object)

Return: a unique integer for a given object

How id() Function Work?

In this example, we can see the function accepts a single parameter and is used to return the identity of an object. This identity has to be unique and constant for this object during its lifetime. Two objects with non-overlapping lifetimes may have the same id() value. If we relate this to C, they are the memory address, here in Python it is the unique ID. This function is generally used internally in Python. 

Python3




x = 42
y = x
z = 42
 
print(id(x)) 
print(id(y))  # (same as x)
print(id(z))  # (same as x and y)
 






                        










Output


140642115230496
140642115230496
140642115230496






Python id() function Examples


Below are the ways with which we can use id() function in Python:


    

  • Inbuilt DataTypes
    • 

  • Custom Object
    • 

  • With Sets
    • 

  • With Tuples
    • 



Python id() for Inbuilt DataTypes


In this example, we are printing the id of multiple datatypes like strings and lists to get object identity in Python




Python3














                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















# This program shows various identities


str1 = "geek"


print(id(str1))


 


str2 = "geek"


print(id(str2))


 


# This will return True


print(id(str1) == id(str2))


 


# Use in Lists


list1 = ["aakash", "priya", "abdul"]


print(id(list1[0]))


print(id(list1[2]))


 


# This returns false


print(id(list1[0])==id(list1[2]))



















                        







                        










Output


140161148229168
140161148229168
True
140161147809712
140161147916400
False






Python id() for custom object


In this example, we are creating the Python class and we are creating two Python class objects and checking their ids to get object identity in Python.




Python3














                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















class MyClass:


    pass


 


# Create two instances of MyClass


obj1 = MyClass()


obj2 = MyClass()


 


# Print the id of each object


print(id(obj1))


print(id(obj2))



















                        







                        










Output


140225741483792
140225741483856






Python id() with Sets


In this example, we are using the id function on sets to get object identity in Python.




Python3














                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















set1 = {1, 2, 3}


set2 = {3, 2, 1}


set3 = {1, 2, 3}


 


print(id(set1))  # Output: <id1>


print(id(set2))  # Output: <id2>


print(id(set3))  # Output: <id3>



















                        







                        










Output


140483509094352
140483509093872
140483509095792






Python id() with Tuples


In this example, we are using the id function on tuples to get object identity in Python.




Python3














                                    




                                    

                                    




                                    




                                    

                                    

                                    
                                




















tuple1 = (1, 2, 3)


tuple2 = (3, 2, 1)


tuple3 = (1, 2, 3)


 


print(id(tuple1))  # Output: <id1>


print(id(tuple2))  # Output: <id2>


print(id(tuple3))  # Output: <id3>



















                        







                        










Output


140544960491680
140544960107456
140544960491680








                                    


                                                                          

                                        

                                                                              

                                                                        

                                        

                                            

                                                

                                                    
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                                                    Chinmoy Lenka                                                

                                            

                                            

            
                                        

                                        

                                            

                                                
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