is not operator — consisting of two keywords
not — tests if the left and right operands refer to a different object—in which case it returns
True. It returns
False if they refer to the same object. For example, the expression
[1, 2, 3] is not [1, 2, 3] returns
True because although both lists are equal, they are two different objects in memory.
The following example shows that both lists
lst_2 are not different
lst_1 != lst_2, but when tested for negative identity
lst_1 is not lst_2, they are still different objects.
>>> lst_1 = [1, 2, 3] >>> lst_2 = [1, 2, 3] >>> lst_1 is not lst_2 True >>> lst_1 != lst_2 False
The difference between the ‘
is not‘ and ‘
!=‘ operators is that ‘
is not‘ compares the object reference of two objects whereas ‘
!=‘ compares the semantic equality of two objects.
Python has two identity operators:
is not. They are used to check if two values or variables reside at the same memory location, i.e., refer to the same object in memory. However, if two variables are equal, this doesn’t imply that they are identical. For example, two lists
[1, 2, 3] and
[1, 2, 3] may be different objects (not identical) but they’re equal in value.
Where to Go From Here?
Enough theory. Let’s get some practice!
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While working as a researcher in distributed systems, Dr. Christian Mayer found his love for teaching computer science students.
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His passions are writing, reading, and coding. But his greatest passion is to serve aspiring coders through Finxter and help them to boost their skills. You can join his free email academy here.