Python Operators

a, b = 17, 5

print(a + b)    # 22  — addition
print(a - b)    # 12  — subtraction
print(a * b)    # 85  — multiplication
print(a / b)    # 3.4 — true division (always float!)
print(a // b)   # 3   — floor division (discard remainder)
print(a % b)    # 2   — modulo (the leftover: 17 = 5×3 + 2)
print(a ** b)   # 1419857  — 17 to the power of 5

# Real-world uses of // and %
minutes = 137
print(f"{minutes // 60}h {minutes % 60}m")  # 2h 17m

number = 42
print(number % 2 == 0)  # True — even numbers have remainder 0

# Negative floor division — rounds toward negative infinity
print(-7 // 2)   # -4  (not -3 — always rounds DOWN)
print(7 // -2)   # -4

age = 20
print(age >= 18)    # True  — is adult?
print(age == 21)    # False — exact match
print(age != 21)    # True  — not equal

# Chained comparisons — very Pythonic!
score = 75
print(60 <= score <= 100)  # True  — is it between 60 and 100?

# Comparing strings (alphabetical order)
print("apple" < "banana")    # True  — 'a' comes before 'b'
print("Python" == "python")  # False — case-sensitive!

# None comparisons — always use is, not ==
result = None
print(result is None)        # True  — correct way
print(result == None)        # True  — works but bad practice

age = 22
has_id = True
is_member = False

# and — both conditions required
print(age >= 18 and has_id)        # True  (22≥18 AND has ID)
print(age >= 18 and is_member)     # False (22≥18 BUT not member)

# or — at least one condition required
print(has_id or is_member)          # True  (has ID, even if not member)
print(not has_id or is_member)      # False (neither True)

# not — invert
print(not is_member)                 # True  (flip False)
print(not (age < 18))                # True  (22 is not < 18)

# Combined — grade checker
score = 78
passed = score >= 50
distinction = score >= 75 and passed
print(f"Passed: {passed}, Distinction: {distinction}")
# Passed: True, Distinction: True

# Simulating a game score counter
score = 0

score += 10   # player hits enemy  → 10
score += 25   # player levels up   → 35
score -= 5    # player takes damage → 30
score *= 2    # double-points bonus → 60
print(score)  # 60

# Using //= to keep a whole number
total_seconds = 3661
hours   = total_seconds // 3600
remain  = total_seconds % 3600
minutes = remain // 60
seconds = remain % 60
print(f"{hours}h {minutes}m {seconds}s")  # 1h 1m 1s

# is / is not — use only for None, True, False
user = None
print(user is None)      # True  — idiomatic Python
print(user is not None)  # False

# in — works on strings, lists, tuples, dicts
print("py" in "python")         # False — case-sensitive!
print("Py" in "Python")         # True
print(3 in [1, 2, 3, 4])       # True
print(5 not in [1, 2, 3])      # True

# Practical: check allowed roles
role = "editor"
allowed = ["admin", "editor", "moderator"]
print(role in allowed)          # True — role is permitted

# Without parentheses — follows precedence rules
print(2 + 3 * 4)       # 14  (* before +)
print(10 - 2 ** 3)     # 2   (** before -)
print(6 / 2 * 3)       # 9.0 (left to right when same level)

# With parentheses — override precedence
print((2 + 3) * 4)     # 20  (+ first now)
print((10 - 2) ** 3)   # 512 (subtraction first)

# Complex expression — use parens for readability
x = 5
# confusing:       # clear:
print(x ** 2 + 2 * x + 1)           # 36 — (x+1)² = 6² = 36
print((x ** 2) + (2 * x) + 1)       # 36 — same, but crystal clear

# Logical precedence trap
print(True or False and False)     # True  (and before or)
print((True or False) and False)   # False (parens change result!)