Membership Operators

What are Membership Operators

These operators are used to check if a given value is a member of a sequence and returns True if it is else it returns False

Membership Operators in Python

There are only two membership operators in Python

in operator

in operator checks if the value is a member of a sequence, and then returns either True if it is a member of that given sequence else returns False

Here’s some examples

In the following examples we’ll be using interactive shell

Example

  >>> name = "Python"
  >>>
  >>> # this expression will return True because y is a member in name
  >>> "y" in name
  True
  >>>
  >>> # the statement below is returning False because 'y' and 'Y' do not have the same value
  >>> "Y" in name
  False
  >>>
  >>> # this expression will return False because z is not a member in name
  >>> "z" in name
  False
  >>>

Warning: When using membership operators with strings, know that "y" and "Y" do not have the same value, so trying to check if capital "Y" is in name where there is only small "y" will always return False

Note: Also when cheking for the existence of sub-string within a sequence, the order matters

not in operator

not in operator exactly does the opposite by checking if the value is not a member of a sequence, and then returns either True if it is not a member of that given sequence else returns False

Here’s some examples

Example

  >>> greeting = "Hello, World"
  >>>
  >>> # the statement below will return False
  >>> "L" in greeting
  False
  >>>
  >>> # the statement below will return True
  >>> "l" in greeting
  True
  >>>
  >>> # the statment below will return True
  >>> "ello" in greeting
  True
  >>>
  >>> # the statment below will return False
  >>> "Ello" in greeting
  False
  >>>