not Operator in Python (original) (raw)
Last Updated : 02 May, 2025
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.
Python `
a = True print(not a)
`
**Practical Applications
The possible practical applications of the “not” keyword are:
- This keyword is mostly used for altering the **boolean value.
- It is used with an if statement. It is used to negate the condition in the if statement.
- 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.
Python `
a = False print(not a)
`
**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.
Python `
print(not False) print(not True)_ print(not(True and False)) print(not(True or False)) print(not (5 > 7))
`
Output
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.
Python `
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)
`
Output
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.
Python `
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")
`
Output
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].
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