bool — Boolean Data Type

Visual reference

What you will learn

• What is bool? — Python’s logical data type
• True and False — the only two boolean values
• 1 and 0 relationship — why booleans work in arithmetic
• Real-world conditions — decisions using if

Big picture: why do we need bool?

Computers constantly make decisions. Every decision eventually becomes one of two answers:

• Yes → True
• No → False

Real-life examples

Question	If True	If False
User logged in?	Open dashboard	Show login
Payment successful?	Confirm order	Show error
Internet available?	Sync data	Offline mode
Notifications enabled?	Send alert	Skip alert

What is bool?

bool is a pre-defined class and a fundamental type.

Purpose: store logical values — only True and False.

True	False
Yes, on, success, enabled	No, off, failure, disabled

Analogy

Think of a light switch: ON = True, OFF = False. There is no third stable state.

Creating boolean variables

is_logged_in = True
is_admin = False

print(is_logged_in)
print(type(is_logged_in))

True
<class 'bool'>

Memory tip: capitalization matters

Correct	Wrong
True, False	true, false

Lowercase names are treated as variables:

# a = true
# NameError: name 'true' is not defined

The hidden secret: bool is a subtype of int

In Python’s execution environment, True is treated as 1 and False as 0.

Verify:

print(int(True))
print(int(False))

1
0

bool is a special numeric type that behaves like integers when needed.

Boolean arithmetic

Since True = 1 and False = 0, arithmetic on booleans is arithmetic on 0 and 1.

Expression	Calculation	Answer
True + False	1 + 0	1
True + True	1 + 1	2
False + False	0 + 0	0
2 * True + 3	2×1 + 3	5

print(True + False)
print(True + True)
print(False + False)

1
2
0

Interactive: try expressions in the playground

Scroll to Try it in the playground at the bottom. Edit expressions like True + False or 2 * True + 3, run again, and watch Python treat True as 1 and False as 0.

Mixing bool with integers

Booleans combine with binary, octal, and hex integers too (from your notes).

print(True + 0b1010)
print(True - False + 0xF)

Example 1: True + 0b1010 → 1 + 10 = 11

Example 2: True - False + 0xF → 1 - 0 + 15 = 16

11
16

Also from your notes:

print(2 * True + 3)    # 5
print(2 * (True + 3))  # 8 — True becomes 1 before (True + 3)

Multiplication step by step

print(2 * True + 3)

5

Division: be careful

Expression	Calculation	Result
True / True	1 ÷ 1	1.0
False / True	0 ÷ 1	0.0
False // True	0 // 1	0
False / False	0 ÷ 0	Error
True / False	1 ÷ 0	Error

print(True / True)
print(False / True)
# print(False / False)  # ZeroDivisionError

False is 0, so False / False is division by zero.

Why is bool useful in programming?

Booleans are mainly for conditions, not clever math.

is_logged_in = True

if is_logged_in:
    print("Welcome!")

Enterprise-style flags

Boolean variable	Meaning
is_authenticated	User logged in?
is_admin	Admin privileges?
email_verified	Email confirmed?
payment_success	Payment completed?
is_deleted	Soft-delete flag

Best practice

Boolean arithmetic is valid in Python, but avoid using it for business logic — it hurts readability.

Recommended:

if is_admin:
    access_dashboard()

Avoid:

if is_admin == True:
    ...

Use booleans to express intent, not clever math.

Practice exercises

1. Predict True + True and False // True before running in the playground.
2. Uncomment False / False once to see ZeroDivisionError.
3. Set is_logged_in = False and run the if block — what prints?

Quick knowledge check

1. Valid boolean keywords?
   True and False (capitalized).

2. What is True + False?
   1.

3. Why does False / False fail?
   Division by zero (0 / 0).

Summary

• bool stores only True and False (logical values).
• Keywords must be capitalized.
• Internally True = 1, False = 0; bool is a subtype of int.
• Arithmetic on booleans works; if is the main real-world use.
• False / False and True / False raise ZeroDivisionError.

Next lesson: complex — complex numbers, j notation, and complex arithmetic.