Python Operators — Arithmetic, Comparison, Logical, and Bitwise Guide

a, b = 10, 3
 
print(a + b)   # 13  — addition
print(a - b)   # 7   — subtraction
print(a * b)   # 30  — multiplication
print(a / b)   # 3.3333... — true division (always returns float)
print(a // b)  # 3   — floor division (integer result)
print(a % b)   # 1   — modulo (remainder)
print(a ** b)  # 1000 — exponentiation
 
# Useful patterns
print(17 % 12)   # 5  — clock arithmetic
print(-7 % 3)    # 2  — Python modulo is always non-negative for positive divisor
print(2 ** 10)   # 1024
print(100 ** 0.5)  # 10.0 — square root via exponentiation

x, y = 5, 10
 
print(x == y)   # False — equal
print(x != y)   # True  — not equal
print(x < y)    # True  — less than
print(x > y)    # False — greater than
print(x <= y)   # True  — less than or equal
print(x >= y)   # False — greater than or equal
 
# Chained comparisons (Pythonic)
age = 25
print(18 <= age <= 65)   # True — between 18 and 65
print(1 < 2 < 3 < 4)     # True — all True

# and, or, not
print(True and False)   # False
print(True or False)    # True
print(not True)         # False
 
# Short-circuit evaluation
def risky():
    raise ValueError("Should not be called")
 
print(False and risky())   # False — risky() never called
print(True or risky())     # True  — risky() never called
 
# Practical use
user = None
name = user and user["name"]   # safely avoid AttributeError
value = user or "default"       # fallback value

x = 10
x += 5    # x = x + 5  → 15
x -= 3    # x = x - 3  → 12
x *= 2    # x = x * 2  → 24
x //= 5   # x = x // 5 → 4
x **= 3   # x = x ** 3 → 64
x %= 10   # x = x % 10 → 4

a = [1, 2, 3]
b = [1, 2, 3]
c = a
 
print(a == b)    # True  — same values
print(a is b)    # False — different objects in memory
print(a is c)    # True  — same object
 
# None comparison — always use 'is'
result = None
if result is None:       # correct
    pass
if result == None:       # works but not idiomatic
    pass
 
# CPython interns small integers and short strings
x = 256
y = 256
print(x is y)   # True  — CPython caches -5 to 256
x = 257
y = 257
print(x is y)   # False — not cached (implementation detail)

fruits = ["apple", "banana", "cherry"]
 
print("apple" in fruits)      # True
print("mango" not in fruits)  # True
 
# String membership
print("py" in "python")       # True
print("xyz" not in "hello")   # True
 
# Dict membership (checks keys)
config = {"host": "localhost", "port": 5432}
print("host" in config)       # True
print("password" in config)   # False
 
# Set membership — O(1) lookup
tags = {"python", "web", "api"}
print("python" in tags)       # True — fastest membership test

a = 0b1100  # 12
b = 0b1010  # 10
 
print(bin(a & b))   # 0b1000 (8)  — AND
print(bin(a | b))   # 0b1110 (14) — OR
print(bin(a ^ b))   # 0b0110 (6)  — XOR
print(bin(~a))      # -0b1101     — NOT (bitwise complement)
print(bin(a << 1))  # 0b11000 (24) — left shift (multiply by 2)
print(bin(a >> 1))  # 0b110 (6)    — right shift (divide by 2)
 
# Practical: check if number is even
def is_even(n: int) -> bool:
    return (n & 1) == 0
 
# Practical: swap without temp variable
x, y = 5, 10
x, y = x ^ y, x ^ y ^ (x ^ y)  # works but use tuple swap instead
x, y = y, x  # simpler and more Pythonic

# Without walrus
data = get_data()
if data:
    process(data)
 
# With walrus (assign and check in one)
if data := get_data():
    process(data)
 
# In while loops
import re
 
text = "Hello 42 World 17"
pos = 0
while match := re.search(r"\d+", text[pos:]):
    print(match.group())
    pos += match.end()
 
# In comprehensions
values = [1, 2, 3, 4, 5, 6]
# Find and use transformed values
results = [y for x in values if (y := x ** 2) > 10]
# [16, 25, 36]