Python Booleans

A Boolean expression is an expression that evaluates to either True or False. For example,

result1 = True
result2 = False

print(result1) # True
print(result2) # False

Here, result1 represents True boolean value and result2 represents False boolean value.

Python Comparison Operators

Python has a set of comparison operators that allow us to compare two values. If the comparison is right, we get True and if the comparison is wrong, we get False.

Let's see an example,

number = 5
print(number < 10) # True

number = 15
print(number < 10) # False

Here, the < comparison operator is used to compare whether number is less than 10 or not.

List of Python Comparison Operators

Examples: Comparison Operators

# comparison operators in action

number = 15
print(number > 10) # True

number = 10
print(number > 10) # False

number = 10
# equal to
print(number == 10) # True

number = 10.0
# comparing float and integer
print(number == 10) # True

number = '10'
# comparing string and integer
print(number == 10) # False

number = '10'
# not equal to
print(number != 10) # True

number = 10
# less than or equal to
print(number <= 10) # True

number = 10
# greater than or equal to
print(number >= 10) # True

Python Logical Operators

Python also has three logical operators that operate on the boolean values. Here's a list of the logical operators:

and Operator in Python

If both of the expressions are True, then the result is True.

age = 22
gpa = 3.8

result = age >= 18 and gpa > 3.6
print(result) # True

However, if either of these expressions is False, the result is False.

age = 22
gpa = 3.8

print(age >= 18 and gpa > 3.9) # False

or Operator in Python

If either of the expressions is True, then the result is True. If both expressions are False, only then the result is False.

age = 22
gpa = 3.8

print(age >= 18 or gpa > 3.9) # True

print(age <= 18 or gpa > 3.9) # False

not Operator in Python

The not operator gives the complement of a given value:

1. If the value is True, it returns False.
2. If the value is False, it returns True.

Let's see an example,

result = True
print(result) # True

result = True
print(not result) # False

Example: Python Booleans, Comparison and Logical Operators

language = 'Python'
print(language == 'python') # False

age = 18
print(age >= 18) # True
print(age > 18) # False

print(age >= 18 and language == 'Java') # False

Output

False
True
False
False

Truthy and Falsy Values in Python

The values that evaluates to True are Truthy values and the values that evaluates to False are Falsy values.

In Python these values are considered falsy.

• None
• False
• 0, 0.0
• empty strings, lists, dictionaries etc.

All other values are considered truthy.

Example: Truthy and Falsy

Suppose we need to find the smallest number between three numbers.

n1 = 60
n2 = 80
n3 = 50

if n1 < n2 and n3:
    print(n1)
elif n2 < n1 and n3:
    print(n2)
else:
    print(n3)

Output

60

Here, we are getting 60 as the smallest number, which is wrong.

Can you find out where the error is?

Take a look at this code:

if n1 < n2 and n3:
    print(n1)

Here, n1 < n2 evaluates to True, and n3 also evaluates to True. So the statement inside the if block is executed.

Instead here's what we should have written:

if n1 < n2 and n1 < n3:
    print(n1)
elif n2 < n1 and n1 < n3:
    print(n2)

Now we will get the actual smallest number i.e 50.

Recommended Reading: Python match...case