Membership Operators in Python

What is Membership Operators

Membership operators in Python are used to check whether a value or variable exists in a sequence, such as a string, list, tuple, set, or dictionary. However, keep in mind that in a dictionary, we can only check for the presence of a key, not the value.

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There are 2 types of membership operators in Python and they are:

• in
• not in

Now let's see the examples of the membership operators one by one for more understanding.

in Operator

The in operator checks if a value or variable exists in a sequence. If it is found, the result is True; otherwise, it is False.

a = "I am learning Python"
b = {1:'apple',2:'ball'}      # it is a dictionary where 1 is key and apple is its value
x = "Python" in a             # output of x is True
y = 3 in b                    # output of y is False

In the example above, the output of x is True because the string 'Python' is present in the variable a. However, the output of y is False because the key 3 is not present in the dictionary b.

not in Operator

The not in operator checks if a value or variable is not present in a sequence. If it is not found, the result is True; otherwise, it is False.

a = "I am learning Python"
b = {1:'apple',2:'ball'}      # it is a dictionary where 1 is key and apple is its value
x = "Hello" not in a          # output of x is True
y = 1 not in b                # output of y is False

In the example above, the output of x is True because the string 'Hello' is not present in the variable a. However, the output of y is False because the key 1 is present in the dictionary b.