Operators

Operators

Arithmetic

a, b = 10, 3
print(a + b)   # 13  — addition
print(a - b)   # 7   — subtraction
print(a * b)   # 30  — multiplication
print(a / b)   # 3.333... — true division (always float)
print(a // b)  # 3   — floor division
print(a % b)   # 1   — modulo
print(a ** b)  # 1000 — exponentiation

Comparison

print(5 == 5)   # True
print(5 != 3)   # True
print(5 > 3)    # True
print(5 < 3)    # False
print(5 >= 5)   # True
print(5 <= 4)   # False

Logical

print(True and False)  # False
print(True or False)   # True
print(not True)        # False

# Short-circuit evaluation
x = None
y = x or "default"    # "default"
z = x and x.upper()   # None (short-circuits)

Assignment

x = 10
x += 5   # x = 15
x -= 3   # x = 12
x *= 2   # x = 24
x /= 4   # x = 6.0
x //= 2  # x = 3.0
x **= 3  # x = 27.0
x %= 5   # x = 2.0

Walrus Operator := (Python 3.8+)

Assigns and returns a value in a single expression:

# Without walrus
data = get_data()
if data:
    process(data)

# With walrus
if data := get_data():
    process(data)

# Useful in while loops
while chunk := file.read(1024):
    process(chunk)

Bitwise

a, b = 0b1010, 0b1100   # 10, 12
print(a & b)   # 8  — AND
print(a | b)   # 14 — OR
print(a ^ b)   # 6  — XOR
print(~a)      # -11 — NOT
print(a << 1)  # 20 — left shift
print(a >> 1)  # 5  — right shift

Identity

a = [1, 2]
b = a
c = [1, 2]

print(a is b)    # True  — same object
print(a is c)    # False — equal but different objects
print(a is not c) # True

Membership

fruits = ["apple", "banana", "cherry"]
print("apple" in fruits)     # True
print("grape" not in fruits) # True

# Works on strings, dicts (checks keys), sets
print("a" in "banana")       # True
print("key" in {"key": 1})   # True

Operator Precedence (high → low)

Precedence	Operators
Highest	**
	+x, -x, ~x (unary)
	*, /, //, %
	+, -
	<<, >>
	&
	^
	|
	==, !=, <, >, <=, >=, is, in
	not
	and
Lowest	or