Boolean Data in Python

Let's dive into the world of boolean data in Python. This topic may seem simple, but it's incredibly important — after all, it's with boolean values that your programs will make decisions! 🧠

What is boolean data?

In everyday life, we often ask questions with "yes" or "no" answers.
For example: "Is it raining today?", "Do you like pizza?", "Is 2 + 2 = 5?".

In Python, there's a special data type for such answers — bool, which can only take two values:

True (truth, "yes") ✅
False (falsehood, "no") ❌

Python 3.13
# Creating boolean variables
>>> is_raining = True  # Yes, it's raining
>>> likes_pizza = True  # Yes, I like pizza

>>> print(type(is_raining))  # <class 'bool'>
<class 'bool'>

💡 Important: True and False are always written with a capital letter. If you write true or false, Python won't understand and will raise an error!

Boolean operators: how to combine conditions

In life, we often combine multiple conditions.
For example: "I'll go to the beach if it's sunny AND warm" or "I'll buy this phone if it's beautiful OR inexpensive".

Python gives us three main logical operators:

1. The and operator (logical AND)

Returns True only if both values are true:

Python 3.13
>>> sunny = True  # It's sunny
>>> warm = True   # It's warm

# I'll go to the beach if it's sunny AND warm
>>> going_to_beach = sunny and warm
>>> print(f"Sunny: {sunny}, Warm: {warm}")
>>> print(f"Going to the beach? {going_to_beach}")
Sunny: True, Warm: True
Going to the beach? True

# What if the weather changes?
>>> warm = False  # It got cold
>>> going_to_beach = sunny and warm
>>> print(f"Sunny: {sunny}, Warm: {warm}")
>>> print(f"Going to the beach? {going_to_beach}")
Sunny: True, Warm: False
Going to the beach? False

2. The or operator (logical OR)

Returns True if at least one value is true:

Python 3.13
>>> phone_is_beautiful = True   # The phone is beautiful
>>> phone_is_cheap = False      # But not cheap

# I'll buy the phone if it's beautiful OR inexpensive
>>> will_buy_phone = phone_is_beautiful or phone_is_cheap
>>> print(f"Phone is beautiful: {phone_is_beautiful}, Phone is cheap: {phone_is_cheap}")
>>> print(f"Will buy the phone? {will_buy_phone}")
Phone is beautiful: True, Phone is cheap: False
Will buy the phone? True

Truth table for the or operator:

Python 3.13
>>> print("True or True =", True or True)
True or True = True
>>> print("True or False =", True or False)
True or False = True
>>> print("False or True =", False or True)
False or True = True
>>> print("False or False =", False or False)
False or False = False

3. The not operator (logical NOT)

Inverts the value: True becomes False, and vice versa:

Python 3.13
>>> have_homework = True
>>> print(f"I have homework: {have_homework}")
I have homework: True
>>> print(f"I DON'T have homework: {not have_homework}")
I DON'T have homework: False

# Another example: if it's not raining, we go for a walk
>>> is_raining = False
>>> going_for_a_walk = not is_raining
>>> print(f"Is it raining? {is_raining}")
Is it raining? False
>>> print(f"Going for a walk? {going_for_a_walk}")
Going for a walk? True

Comparing values

Boolean values often appear as a result of comparison:

Python 3.13
# Comparing numbers
>>> my_age = 25
>>> friend_age = 30

>>> print(f"My age: {my_age}, friend's age: {friend_age}")
My age: 25, friend's age: 30
>>> print(f"Our ages are the same? {my_age == friend_age}")
Our ages are the same? False
>>> print(f"Our ages are different? {my_age != friend_age}")
Our ages are different? True
>>> print(f"Am I younger? {my_age < friend_age}")
Am I younger? True
>>> print(f"Am I older? {my_age > friend_age}")
Am I older? False

# Comparing strings (alphabetically)
>>> print("String comparison:")
String comparison:
>>> print(f"'apple' < 'banana': {'apple' < 'banana'}")
'apple' < 'banana': True
>>> print(f"'python' == 'Python': {'python' == 'Python'}")
'python' == 'Python': False

# Comparing lists
>>> my_scores = [90, 85, 95]
>>> friend_scores = [90, 85, 95]  # Same list, but different object
>>> same_list = my_scores  # The same object

>>> print("List comparison:")
List comparison:
>>> print(f"Contents the same? {my_scores == friend_scores}")
Contents the same? True
>>> print(f"Is it the same object? {my_scores is friend_scores}")
Is it the same object? False
>>> print(f"Is same_list the same object as my_scores? {my_scores is same_list}")
Is same_list the same object as my_scores? True

Operator precedence: what gets calculated first?

Operators are executed in the following order (from highest to lowest):

not (highest priority)
and
or (lowest priority)

Python 3.13
# Example with priorities
>>> has_ticket = True
>>> has_passport = False
>>> has_visa = True

>>> print(f"Have ticket: {has_ticket}")
Have ticket: True
>>> print(f"Have passport: {has_passport}")
Have passport: False
>>> print(f"Have visa: {has_visa}")
Have visa: True

# Can we travel abroad?
# Need a ticket AND (passport OR visa)
>>> can_travel = has_ticket and (has_passport or has_visa)
>>> print("\nCan we travel abroad?")

Can we travel abroad?
>>> print(f"has_ticket and (has_passport or has_visa) = {can_travel}")
has_ticket and (has_passport or has_visa) = True

# Let's break down the calculation step by step:
>>> step1 = has_passport or has_visa  # First, the expression in parentheses is calculated
>>> print(f"\nStep 1: has_passport or has_visa = {step1}")

Step 1: has_passport or has_visa = True

>>> step2 = has_ticket and step1  # Then the and operator is applied
>>> print(f"Step 2: has_ticket and (result of step 1) = {step2}")
Step 2: has_ticket and (result of step 1) = True

💡 Tip: If you're unsure about the order of execution, use parentheses! They make the code clearer and precisely control the order of calculations.

Converting to boolean type: what counts as true?

The bool function

Python can convert any value to a boolean type:

Python 3.13
print(bool(100))
True
print(bool(0))
False
print(bool("Hello"))
True
print(bool(""))
False

What counts as true and false?

In Python, most values are considered true (True).

Only the following are considered false (False):

False (the logical "no")
None (absence of value)
Zeros: 0, 0.0, 0j
Empty containers: "", (), [], {}

Python 3.13
# Examples in conditions
money = 0
if money:
    print("I have money!")
else:
    print("My wallet is empty :(")  # This will be printed

name = "Alex"
if name:
    print(f"Hello, {name}!")  # This will be printed
else:
    print("Hello, stranger!")

Understanding check

Let's check how well you've understood the material:

What will the following expression return?

Python 3.13
result = (False or True) and not (False and True or True)

Now you know how boolean data works in Python. Although they can only take two values — True and False, their importance in programming cannot be overstated.