not Operator in Python

The not keyword in Python is a logical operator used to obtain the negation or opposite Boolean value of an operand.

• It is a unary operator, meaning it takes only one operand and returns its complementary Boolean value.
• For example, if False is given as an operand to not, it returns True and vice versa.

Example: Basic example of not operator with True. Here, we used "not" operator to change the true value to false which is the negation of True.

a = True
print(not a)

False

Practical Applications

The possible practical applications of the "not" keyword are: 

1. This keyword is mostly used for altering the boolean value.
2. It is used with an if statement. It is used to negate the condition in the if statement.
3. The "not" keyword is also used with "in keyword". It is used with the "in" keyword when we are searching for a specific value in a collection of data.

Examples of Not Operator

Let's look at some examples of not operator in Python codes, each example shows different use-cases of "not" operator.

Example 1: Python "not" operator with Variables

Basic example of "not" operator with variable.

a = False
print(not a)

True

Explanation: The not operator negates the value of a, turning False into True.

Example 2: Using the "not" Boolean Operator in Python with Specific condition

This example shows various ways to use the not operator with different Boolean values and expressions.

print(not False)
print(not True)_
print(not(True and False))
print(not(True or False))
print(not (5 > 7))

True
False
True
False
True

Explanation: The not operator negates each Boolean expression. For example, not True becomes False and not(False and True) becomes True.

Example 3: Using the Not Operator with different Value

This example demonstrates the behavior of the not operator with different data types like strings, lists and dictionaries.

s = "geek"
print(not s)

a = [1, 2, 3, 4]
print(not a)

d = {"geek": "sam", "collage": "Mit"}
print(not d)

es = ""
print(not es)

el = []
print(not el)

ed = {}
print(not ed)

False
False
False
True
True
True

Explanation: The not operator returns False for non-empty values (strings, lists, dictionaries) and True for empty ones. For example, not "geek" is False and not "" is True.

Example 4: Logical NOT operator with the list

This example uses the not operator in a condition to check the properties of items in a list.

a = [5, 10, 20, 59, 83]
if not a:
    print("Inputted list is Empty")
else:
    for i in a:
        if not(i % 5):
            if i not in (0, 10):
                print(i,"is not in range")
            else:
                print(i, "in range")
        else:
            print(i,"is not multiple of 5")

5 is not in range
10 in range
20 is not in range
59 is not multiple of 5
83 is not multiple of 5

Explanation: The not operator is used to check if the list a is empty or if a number is a multiple of 5. If the list is empty, it prints "Inputted list is Empty". It also checks for numbers not in the range [0, 10].

Related Articles:

• logical operator
• boolean value
• if statement
• in keyword