Python’s in and not in operators allow you to quickly check if a given value is or isn’t part of a collection of values. This type of check is generally known as a membership test in Python.

When you write a not in b it is using the not in operator, whereas not a in b uses the in operator and then negates the result. But the not in operator is defined to return the same as not a in b so they do exactly the same thing.

Apr 24, 2020 · In the Python programming language, there are two membership operators “in” and “not in” that can be used when you want to check whether a value or item is present in an iterator. “in” returns True if it is present and if it is not present it returns False, while “not in” is just the opposite, it returns False if it is present ...

Aug 17, 2017 · The statements if x in a: and for x in a: do not have much to do with each other, they simply feature the same word in, but it has different meaning. You could easily imagine how one would implement a feature similar to if x in a: in c++ - for instance use std::find.

Feb 13, 2025 · Python NOT IN Operator The ‘not in’ Python operator evaluates to true if it does not find the variable in the specified sequence and false otherwise.

Apr 2, 2024 · Membership operators in Python, such as “in” and “not in,” check if a value exists in a sequence like a list, tuple, or string. On the other hand, identity operators “is” and “is not,” are used to compare the memory locations of two objects.

Mar 18, 2025 · In Python, the keywords in and not in are powerful tools that play a crucial role in various programming tasks. They are used to check for the existence of an element within a container (such as a list, tuple, set, or dictionary) or to negate that check.

So both of them are Boolean operators, so they return True or False depending on the result of the membership check. 00:18 The general form is that if you use the in operator, then you say value in container. And if you use the not in operator, …

In this video course, you'll learn how to check if a given value is present or absent in a collection of values using Python's in and not in operators. This type of check is known as a membership test in Python.

Apr 17, 2025 · In and not in operators can reduce multiple lines of logic to one expressive line. But like all tools, they come with caveats. Let’s explore how they work, when to use them, and when to think twice before using them. What Do in and not in Actually Do? Python’s in operator checks whether a value exists in a container.