Python id()

The id() function returns identity (unique integer) of an object.

The syntax of id() is:


id() Parameters

id() function takes a single parameter object.

Return Value from id()

id() function returns the identity of the object. This is an integer that is unique for the given object and remains constant during its lifetime.

Example 1: How id() works?

class Foo:
    b = 5

dummyFoo = Foo()
print('id of dummyFoo =',id(dummyFoo))


id of dummyFoo = 140343867415240

More Examples on id()

print('id of 5 =',id(5))

a = 5
print('id of a =',id(a))

b = a
print('id of b =',id(b))

c = 5.0
print('id of c =',id(c))


id of 5 = 140472391630016
id of a = 140472391630016
id of b = 140472391630016
id of c = 140472372786520

It's important to note that everything in Python is an object, even numbers, and Classes.

Hence, integer 5 has a unique id. The id of the integer 5 remains constant during the lifetime. Similar is the case for float 5.5 and other objects.