Python Booleans

Basic Boolean Values

Python has two boolean literals: True and False

# Boolean literals
is_sunny = True
is_raining = False

print(f"Is it sunny? {is_sunny}")      # True
print(f"Is it raining? {is_raining}")  # False
print(f"Type of is_sunny: {type(is_sunny)}")  # 

# Boolean from simple comparisons
age = 25
is_adult = age >= 18
print(f"Is adult? {is_adult}")  # True

# Boolean in conditions
if is_sunny:
    print("Great day for a picnic!")
else:
    print("Maybe stay indoors.")

Boolean from Comparisons

Most boolean values come from comparison operations

🔹 Numeric Comparisons

a = 10
b = 20

# Equal to
print(f"Is a equal to b? {a == b}")  # False

# Not equal to 
print(f"Is a not equal to b? {a != b}")  # True

# Less than
print(f"Is a less than b? {a < b}")  # True

# Greater than
print(f"Is a greater than b? {a > b}")  # False

🔹 String Comparisons

name1 = "Alice"
name2 = "Bob"

# Compare if strings are equal
print(f"Is name1 equal to name2? {name1 == name2}")  # False

# Compare strings alphabetically
print(f"Does name1 come before name2? {name1 < name2}")  # True

🔹 Type Comparisons

# Comparing different types
number = 5
text = "5"
decimal = 5.0

print(f"Is number equal to text? {number == text}")  # False
print(f"Is number equal to decimal? {number == decimal}")  # True

Logical Operators

Combine multiple boolean values using and, or, not

🔹 AND Operator

Both conditions must be True for the result to be True

age = 25
has_license = True

can_drive = age >= 18 and has_license
print(f"Can drive? {can_drive}")  # True

🔹 OR Operator

At least one condition must be True for the result to be True

is_weekend = True
is_holiday = False

can_sleep_in = is_weekend or is_holiday
print(f"Can sleep in? {can_sleep_in}")  # True

🔹 NOT Operator

Reverses the boolean value

is_working = True
is_free = not is_working
print(f"Is free? {is_free}")  # False

🔹 Combined Operators

You can combine multiple operators together

temp = 75
is_sunny = True

nice_day = temp > 60 and temp < 85 and is_sunny
print(f"Is it a nice day? {nice_day}")  # True

Truthiness and Falsiness

Many values can be evaluated in a boolean context

# Let's see what Python considers True and False
print("Things that are False:")
print(bool(False))  # False
print(bool(0))      # False 
print(bool(""))     # False (empty string)

print("\nThings that are True:")
print(bool(True))   # True
print(bool(1))      # True
print(bool("hi"))   # True

# Check if a list has anything in it
fruits = []
if fruits:
    print("We have fruits!")
else:
    print("No fruits yet")

Boolean in Numeric Context

In Python, True equals 1 and False equals 0 when used in math

# Converting True and False to numbers
print(f"True equals: {int(True)}")   # 1
print(f"False equals: {int(False)}") # 0

# Simple math with True and False
print(f"True + True = {True + True}")   # 2
print(f"True * 3 = {True * 3}")        # 3

# A basic example: Counting passing grades
grades = [95, 85, 55, 75]
passing_grades = sum(grade >= 60 for grade in grades)
print(f"Number of passing grades: {passing_grades}")  # 3

Practical Boolean Examples

Real-world applications of boolean logic

# Simple login check
def check_login(username, password):
    """Check if login is valid"""
    
    # Check if username and password are correct
    if username == "user" and password == "pass123":
        print("Welcome!")
        return True
    else:
        print("Wrong username or password")
        return False

# Test the login
logged_in = check_login("user", "pass123")
print(f"Login successful: {logged_in}")  # True

# Simple age check
def can_watch_movie(age):
    """Check if person can watch a PG-13 movie"""
    
    if age >= 13:
        print("You can watch the movie!")
        return True
    else:
        print("Sorry, you're too young")
        return False

# Test age check
allowed = can_watch_movie(15)
print(f"Can watch movie: {allowed}")  # True