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Logical Operator “not”

In certain instances, you’ll want to check for the opposite of a value. The “not” operator is used for just that. It essentially returns the opposite of whatever the current value is. Let’s try it out:


# using the keyword 'not' within an 'if statement' flag = False if not flag: # same as saying if not true print("Flag is False")

Go ahead and run that cell. You’ll notice that the resulting output is “Flag is False”. This is due to the “not” operator, which took the opposite value of False and made the condition return True.
Note We get the same result if we write “if flag == False:”.

Membership Operators

Membership operators are used to test if a sequence appears in an object. There are two keywords that we can use to check if a value exists in an object or not. Let’s check them out.

Membership Operator “in”

When you want to check if a given object has a value appear in it, you use the “in” operator. The best use case is checking for a certain value within strings. Let’s check out an example:

# using the keyword 'in' within an 'if statement' word = "Baseball" if "b" in word: print( "{ } contains the character b".format(word) )

Go ahead and run that cell. The resulted output is “Baseball contains the character b”. This is case sensitive, but lucky for us the word Baseball has one lowercase and one uppercase b.

Membership Operator “not in”

Likewise, if you want to check to see if an object doesn’t include a specific value, you would use the “not in” operator. This is essentially just checking the opposite of the “in” operator. Let’s see:

# using the keyword 'not in' within an 'if statement' word = "Baseball" if "x" not in word: print( "{ } does not contain the character x".format(word) )

Go ahead and run that cell. The resulting output is “Baseball does not contain the character x”. It simply checks to see if the character x is not included in the string value of our word variable.