04_boolean_tutorial.py

# 1. Boolean values
# There are only two values: True and False (capitalized!)
is_active = True
is_deleted = False

print(f"is_active: {is_active}, type: {type(is_active)}")
print(f"is_deleted: {is_deleted}")

# 2. Comparison operators (return boolean)
x = 10
y = 5

print(f"{x} == {y}: {x == y}")    # Equal: False
print(f"{x} != {y}: {x != y}")    # Not equal: True
print(f"{x} > {y}: {x > y}")      # Greater than: True
print(f"{x} < {y}: {x < y}")      # Less than: False
print(f"{x} >= {y}: {x >= y}")    # Greater or equal: True
print(f"{x} <= {y}: {x <= y}")    # Less or equal: False

# 3. Logical operators
a = True
b = False

print(f"{a} and {b}: {a and b}")    # AND (both must be True): False
print(f"{a} or {b}: {a or b}")      # OR (at least one True): True
print(f"not {a}: {not a}")          # NOT (inversion): False

# 4. Combining conditions
age = 25
has_license = True

# Can drive a car if age >= 18 AND has license
can_drive = age >= 18 and has_license
print(f"Can drive: {can_drive}")

# 5. Logical operator precedence
# not > and > or
result = True or False and False
print(f"True or False and False = {result}")  # True (and first, then or)

# With parentheses for clarity
result = True or (False and False)
print(f"True or (False and False) = {result}")  # True

# 6. Values interpreted as False (Falsy values)
# False, None, 0, 0.0, "", [], {}, ()
print(f"bool(False): {bool(False)}")      # False
print(f"bool(None): {bool(None)}")        # False
print(f"bool(0): {bool(0)}")              # False
print(f"bool(0.0): {bool(0.0)}")          # False
print(f"bool(''): {bool('')}")            # False (empty string)
print(f"bool([]): {bool([])}")            # False (empty list)
print(f"bool({{}}): {bool({})}")          # False (empty dictionary)

# 7. Values interpreted as True (Truthy values)
# Everything else
print(f"bool(True): {bool(True)}")        # True
print(f"bool(1): {bool(1)}")              # True
print(f"bool('text'): {bool('text')}")    # True
print(f"bool([1,2,3]): {bool([1, 2, 3])}")  # True

# 8. Using in conditions
name = "Pavel"

# Short check for emptiness
if name:
    print(f"Name is specified: {name}")
else:
    print("Name is empty")

# 9. Comparison chaining (unique Python feature!)
age = 25
# Check if age is in range from 18 to 65
if 18 <= age <= 65:
    print(f"Age {age} is in valid range")

# Equivalent (but less readable):
if age >= 18 and age <= 65:
    print("Age is in valid range")

# 10. The 'is' operator (identity check, not equality)
# 'is' checks if two variables reference THE SAME object in memory
a = [1, 2, 3]
b = [1, 2, 3]
c = a

print(f"a == b: {a == b}")    # True (values are equal)
print(f"a is b: {a is b}")    # False (different objects)
print(f"a is c: {a is c}")    # True (same object)

# Important: for None always use 'is', not ==
value = None
if value is None:
    print("Value is None")

# 11. The 'in' operator (membership check)
fruits = ["apple", "banana", "orange"]
print(f"'banana' in fruits: {'banana' in fruits}")          # True
print(f"'pear' not in fruits: {'pear' not in fruits}")      # True

text = "Python"
print(f"'Py' in text: {'Py' in text}")  # True