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Python not Keyword

By IncludeHelp Last updated : December 07, 2024

Description and Usage

not is a keyword (case-sensitive) in python, it is a logical operator actually, it is used with a single operand, it returns True – if the condition evaluated to False and returns False – if the condition evaluated to True.

In other words, we can say, if the condition is True – it returns False and if the condition is False – it returns True.

Truth Table

Truth table for "not" keyword/operator

Condition	not(Condition)
True		False
False 		True

Syntax

Syntax of not keyword/operator:

not(condition)

Sample Input/Output

Input:
a = 10

# conditions
print(not(a == 10))
print(not(a != 10))

Output:
False
True

Example 1

Take a number and test the conditions using not operator

# python code to demonstrate example of
# not  keyword/operator

a = 10

# printing return values
print(not(a == 10))
print(not(a != 10))
print(not(a > 10))
print(not(a < 10))

Output

False
True
True
True

Example 2

Input any number and print its square, if number is not 0

# Input any number and print its square, 
# if number is not 0

num = int(input("Enter a number: "))

# checking the condition and 
# calculate square
if not(num==0):
    square = num*num;
    print("Square of ", num, " is = ", square)
else:
    print("An invalid input.")

Output

First run:
Enter a number: 21
Square of  21  is =  441

Second run:
Enter a number: 0
An invalid input.