Boolean data type in Python

Python boolean type is one of the built-in data types provided by Python, which represents one of the two values i.e. True or False. Generally, it is used to represent the truth values of the expressions.

Example

Input: 1==1
Output: True 

Input: 2<1 
Output: False

Python Boolean Type

The boolean value can be of two types only i.e. either True or False. The output <class ‘bool’> indicates the variable is a boolean data type.

Python3

a = True
type(a)

b = False
type(b)

Output:

<class 'bool'>
<class 'bool'>

Evaluate Variables and Expressions

We can evaluate values and variables using the Python bool() function. This method is used to return or convert a value to a Boolean value i.e., True or False, using the standard truth testing procedure. 

Syntax:

bool([x])

Python bool() Function

We can also evaluate expressions without using the bool() function also. The Boolean values will be returned as a result of some sort of comparison. In the example below the variable res will store the boolean value of False after the equality comparison takes place.

Python3

# Python program to illustrate
# built-in method bool()

# Returns False as x is not equal to y
x = 5
y = 10
print(bool(x==y))

# Returns False as x is None
x = None
print(bool(x))

# Returns False as x is an empty sequence
x = ()
print(bool(x))

# Returns False as x is an empty mapping
x = {}
print(bool(x))

# Returns False as x is 0
x = 0.0
print(bool(x))

# Returns True as x is a non empty string
x = 'GeeksforGeeks'
print(bool(x))

Output

False
False
False
False
False
True

Boolean value from the expression

In this code, since a is assigned the value 10 and b is assigned the value 20, the Python comparison a == b evaluates to False. Therefore, the code will output False.

Python3

# Declaring variables
a = 10
b = 20

# Comparing variables
print(a == b)

Output:

False

Integers and Floats as Booleans

Numbers can be used as bool values by using Python’s built-in bool() method. Any integer, floating-point number, or complex number having zero as a value is considered as False, while if they are having value as any positive or negative number then it is considered as True.

Python3

var1 = 0
print(bool(var1))

var2 = 1
print(bool(var2))

var3 = -9.7
print(bool(var3))

Output:

False
True
True

Boolean Operators

Boolean Operations in Python are simple arithmetic of True and False values. These values can be manipulated by the use of boolean operators which include AND, Or, and NOT. Common boolean operations are –

• or
• and
• not
• == (equivalent)
• != (not equivalent)

Boolean OR Operator

The Boolean or operator returns True if any one of the inputs is True else returns False.

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

Python Boolean OR Operator

In the example, we have used a Python boolean with an if statement and OR operator that checks if a is greater than b or b is smaller than c and it returns True if any of the conditions are True (b<c in the above example).

Python3

# Python program to demonstrate
# or operator

a = 1
b = 2
c = 4

if a > b or b < c:
    print(True)
else:
    print(False)

if a or b or c:
    print("Atleast one number has boolean value as True")

Output

True
Atleast one number has boolean value as True

Boolean And Operator

The Boolean operator returns False if any one of the inputs is False else returns True.

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

Python Boolean And Operator

In the first part of the code,  the overall expression a > b and b < c evaluates to False. Hence, the code will execute the else block and print False. Whereas in the second part, a is 0, conditions a and b, and c will evaluate to False because one of the variables (a) has a boolean value of False. Therefore, the code will execute the else block and print “At least one number has a boolean value as False”.

Python3

# Python program to demonstrate
# and operator

a = 0
b = 2
c = 4

if a > b and b<c:
    print(True)
else:
    print(False)

if a and b and c:
    print("All the numbers has boolean value as True")
else:
    print("Atleast one number has boolean value as False")

Output

False
Atleast one number has boolean value as False

Boolean Not Operator

The Boolean Not operator only requires one argument and returns the negation of the argument i.e. returns the True for False and False for True.

A	Not A
True	False
False	True

Python Boolean Not Operator

The code demonstrates that when the value of a is 0, it is considered falsy, and the code block inside the if statement is executed, printing the corresponding message.

Python3

# Python program to demonstrate
# not operator

a = 0

if not a:
    print("Boolean value of a is False")

Output

Boolean value of a is False

Boolean == (equivalent) and != (not equivalent) Operator

Both operators are used to compare two results. == (equivalent operator returns True if two results are equal and != (not equivalent operator returns True if the two results are not same.

Python Boolean == (equivalent) and != (not equivalent) Operator

The code assigns values to variables a and b and then uses conditional statements to check if a is equal to 0, if a is equal to b, and if a is not equal to b. It prints True for the first and third conditions.

Python3

# Python program to demonstrate
# equivalent an not equivalent
# operator

a = 0
b = 1

if a == 0:
    print(True)

if a == b:
    print(True)

if a != b:
    print(True)

Output

True
True

Python is Operator

The is keyword is used to test whether two variables belong to the same object. The test will return True if the two objects are the same else it will return False even if the two objects are 100% equal.

Python is Operator

The code first assigns the value 10 to variables x and y. It then compares x and y using the “is” operator and prints True because they refer to the same object. Next, it assigns two separate lists to x and y. It then compares x and y using the “is” operator and prints False because the lists are different objects in memory. 

Python3

# Python program to demonstrate
# is keyword


x = 10
y = 10

if x is y:
    print(True)
else:
    print(False)

x = ["a", "b", "c", "d"]
y = ["a", "b", "c", "d"]

print(x is y)

Output

True
False

Python in Operator

in operator checks for the membership i.e. checks if the value is present in a list, tuple, range, string, etc.

Python in Operator

The code creates a list of animals and checks if the string “lion” is present in the list. If “lion” is found in the list, it prints “True”.

Python3

# Python program to demonstrate
# in keyword

# Create a list
animals = ["dog", "lion", "cat"]

# Check if lion in list or not
if "lion" in animals:
    print(True)

Output

True