Logical Operators in Python Language

Topic: Logical Operators in Python Language

Logical Operators in Python Language are used to create compound conditions. The compound conditions contain more than one conditions combined with logical operators. We use ‘and’ and ‘or’ logical operators to combine two or more conditions. Another logical operator ‘not’ is used to reverse the result of a condition.

a=5
b=10

if a==5 and b==10:
   print('Both conditions are True')

The Result: Both conditions are True


a=50
b=10

if a==5 and b==10:
   print('Both conditions are True')
else:
   print('Any one or Both conditions are False')
The Result: Any one or Both conditions are False

gender='male'
city = 'RYK'

if gender == 'male' or city == 'RYK':
   print('Either candidate is male or from RYK city')
else:
   print('Both conditions are wrong')
The Result: Either candidate is male or from RYK city

gender='female'
city = 'SDK'

if gender == 'male' or city == 'RYK':
   print('Either candidate is male or from RYK city')
else:
   print('Both conditions are wrong')
The Result: Both conditions are wrong

We use the Python comparison operators to create Python conditions like a > b or age>=18.

Purpose of Logical Operators in Python Language

We will use Python Logical operators if we want to combine two or more conditions or if we wish to reverse a condition.

Types of Logical Operators in Python

There are three types of the logical operators in Python:

1. Logical ‘and’ operator
2. Logical ‘or’ operator
3. Logical ‘not’ operator

 

LOGICAL OPERATOR	DEFINITION	EXAMPLE	VALUES	RESULT
Logical ‘and’	‘and’ will return true when the both conditions are true	print(a==5 and b==10)	a=5 b=10	True
Logical ‘or’	‘or’ will return true when at least one of the given conditions is true	print(a==5 or b==90)	a=5 b=10	True
Logical ‘not’	‘not’ will revert the result	print(not a==b)	a=5 b=10	True {since a==b will give false and ‘not’ will convert the result to True }

The Use of Logical ‘and’ Operator in Python

The ‘and’ logical operator is used in the progamming situations when we wish to have both conditions are true.

We say, ‘and’ logical operator will gives a True if both of the given condtions produce True result.

Example of ‘and’ Logical Operator

For example, if we wish to check for conditions like male and adult candidate for a job, we will write the two following conditions using logical ‘and’ operator and comparison operators:

if gender =’male’ and age>=18:
print(“A valid candidate: Male and Adult”)
else:
print(“Not a valid candiadate”)

Output: if we assume the following values for the variables:
age = 20
gender = ‘male’

Then the output will be:
A valid candidate: Male and Adult

On the other hand, if we assume the following values:
age = 17
gender = ‘male’

or

age = 20
gender = ‘female’

Then the output will be

Not a valid candiadate

The Truth Table for Logical ‘and’ Operator

A	B	A and B
True	True	True
True	False	False
False	True	False
False	False	False

The Use of Logical ‘or’ Operator in Python

The Logical ‘or’ operator is used in the progamming situations when we wish to have any one condition is true. That is, ‘or’ operator will give a True if any one of the two given conditions is True.

We say, ‘or’ logical operator will gives a True if any one of the both of the given condtions produce True result.

Example of ‘or’ Logical Operator

For example, if we wish to check for conditions like a valid candidate is either with an overall first division result of if he / she has experience of 5 or more years. We will  write the two following conditions using logical ‘or’ operator and comparison operators:

if division = ‘first’ or experience >=5:
print(“A valid candidate”)
else:
print(“Not a valid candiadate”)

Output: if we assume the following values for the variables:
division =’first’
experience = 6

Then the output will be:
A valid candidate: Male and Adult

On the other hand, if we assume the following values:
age = 17
gender = ‘male’

or

age = 20
gender = ‘female’

Then the output will be

Not a valid candiadate

The Truth Table for Logical ‘or’ Operator

A	B	A or B
True	True	True
True	False	True
False	True	True
False	False	False

 

The Use of  ‘not’ Logical Operator in Python

The logical operator ‘not’ is used to reverse the result of a given condition.

Example of ‘not’ Logical Operator in Python Language

a==50

print(a==50)

Result: True

print(not a==50)

Result: False   [not since result of a==50 is True so after reversing the result is False]

The Truth Table for Logical ‘not’ Operator

A	not  A
True	False
False	True