Membership Operators

Membership operators are tools that can helps us determine if a certain value is inside a list or string.

‍These membership operators are:

1. in : evaluates to True if it finds a value inside a sequence, otherwise, it will evaluate to False.
2. not in : evaluates to True if it doesn't find a value inside a sequence, otherwise, it will evaluate to False.

Using Membership operators on lists

Using the in membership operator

Let's assume a list of months:

months = ['January', 'February', 'April']

let's check if June is inside this list:

print( 'June' in months )

>> False

Since June is not inside months, the boolean evaluation will be False.

If I switch the value to January:

print( 'January' in months )

>> True

The evaluation turns to True, since January is available inside the list months.

Using the not in membership operator

On the other hand, if you switch in with not in :

print( 'January' not in months )‍

>‍> False

it will evaluate to False, since January is available in the list.

‍Using Membership operators on strings

Using the in membership operator

W‍ith membership operators, the same concept can be applied to strings, for example:

course = 'Python Crash Course'
print( 'Crash' in course )

‍>> True

since the word crash is available in the list of characters course, the operation will evaluate to True.

change the value to rash

print( 'rash' in course )

>> True

and it still evaluates to True, this is because the set of characters in rash are available in the string course

Now if we change the value to random characters:

print( 'frfr' in course )

>> False

Using the not in membership operator

Using the not in operator also works the same way as it did for lists. In this case:

print('frfr' not in course)

>> True

since frfr is not available in the string course, we get an evaluation of True.