Python id() Function

Last Updated : 29 Aug 2026

Python id() function returns an identity of an object. This is an integer which is guaranteed to be unique. This function takes an argument an object and returns a unique integer number which represents identity. Two objects with non-overlapping lifetimes may have the same id() value.

Syntax of id() Function

It has the following syntax:

Parameters

object: It is an object of which id is to be returned.

Return Values

It returns a unique integer number.

Examples of Python id() Function

Let's see some examples of id() function to understand it's functionality.

Example 1: Using id() Function to Get Memory Address of Objects

This example demonstrates how the id() function returns the unique identity (memory address) of different objects in Python.

Python

# Python id() function example
# Calling function
val = id("Javatpoint") # string object
val2 = id(1200) # integer object
val3 = id([25,336,95,236,92,3225]) # List object
# Displaying result
print(val)
print(val2)
print(val3)

Execute Now

Output:

139963782059696
139963805666864
139963781994504

Example 2: Using id() Function with User-Defined Class Object

This example demonstrates how the id() function is used to get the unique identity of a user-defined class object in Python.

Python

# Python id() function example
class Student:
    def __init__(self, id, name):
        self.id = id
        self.name = name
        
student = Student(101,"Mohan")        
print(student.id)
print(student.name)
# Calling function
val = id(student) # student class object
# Displaying result
print("Object id:",val)

Execute Now

Output:

101
Mohan
Object id: 140157155861392

Example 3: Comparing Object Equality and Identity using id() Function

This example demonstrates the difference between object equality (==) and object identity (id()) in Python.

Python

# Python id() function example
l1 = [1,2,3,4]
l2 = [1,2,3,4]
l3 = [3,5,6,7]
# Calling function
id1 = id(l1)
id2 = id(l2)
id3 = id(l3)
# Displaying result
print((l1==l2),(l1==l3))
# Objects with the same values can have different ids
print((id1==id2),(id1==id3))
# l1 and l2 returns True, while id1 and id2 returns False

Execute Now

Output:

True False
False False

Next TopicPython Set

← prev next →

We deliver comprehensive tutorials, interview question-answers, MCQs, study materials on leading programming languages and web technologies like Data Science, MEAN/MERN full stack development, Python, Java, C++, C, HTML, React, Angular, PHP and much more to support your learning and career growth.