Python Operators - Complete Guide

# Basic arithmetic
x = 10
y = 3

print(x + y)    # Addition: 13
print(x - y)    # Subtraction: 7
print(x * y)    # Multiplication: 30
print(x / y)    # Division: 3.3333... (returns float)
print(x // y)   # Floor division: 3 (returns integer)
print(x % y)    # Modulus: 1 (remainder)
print(x ** y)   # Exponentiation: 1000 (x raised to power y)

# Comparison operators
x = 10
y = 5

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

# Chained comparisons
age = 25
print(18 <= age < 65)  # Check if age is between 18 and 65: True

# Basic assignment
x = 10

# Combined operators
x += 5      # Same as: x = x + 5, Now x is 15
x -= 3      # Same as: x = x - 3, Now x is 12
x *= 2      # Same as: x = x * 2, Now x is 24
x /= 6      # Same as: x = x / 6, Now x is 4.0 (note: becomes float)
x //= 2     # Same as: x = x // 2, Now x is 2.0
x **= 3     # Same as: x = x ** 3, Now x is 8.0
x %= 3      # Same as: x = x % 3, Now x is 2.0

# Works with strings too
message = "Hello"
message += " World"  # message becomes "Hello World"

# Logical operators
x = 10
y = 5

# and - True if both conditions are True
print(x > 5 and y < 10)    # True (both conditions are True)
print(x < 5 and y < 10)    # False (first condition is False)

# or - True if at least one condition is True
print(x > 5 or y > 10)     # True (first condition is True)
print(x < 5 or y > 10)     # False (both conditions are False)

# not - Inverts the boolean value
print(not x > 5)           # False (inverts True to False)
print(not x < 5)           # True (inverts False to True)

# Short-circuit evaluation
result = x > 0 and (x / 0)  # Would cause ZeroDivisionError, but second part is never evaluated

# Bitwise operators
a = 60    # Binary: 0011 1100
b = 13    # Binary: 0000 1101

# & (AND) - Sets bit to 1 if both bits are 1
print(a & b)       # 12 (Binary: 0000 1100)

# | (OR) - Sets bit to 1 if either bit is 1
print(a | b)       # 61 (Binary: 0011 1101)

# ^ (XOR) - Sets bit to 1 if only one bit is 1
print(a ^ b)       # 49 (Binary: 0011 0001)

# ~ (NOT) - Inverts all bits
print(~a)          # -61 (Binary: 1100 0011 with 2's complement)

# << (Left Shift) - Shifts bits left by specified number
print(a << 2)      # 240 (Binary: 1111 0000)

# >> (Right Shift) - Shifts bits right by specified number
print(a >> 2)      # 15 (Binary: 0000 1111)

# Practical example: Binary flags
READ = 1        # 0001
WRITE = 2       # 0010
EXECUTE = 4     # 0100

# Grant read and write permissions
permissions = READ | WRITE    # 3 (0011)

# Check if write permission exists
has_write = permissions & WRITE  # 2 (non-zero means True)

# Identity operators: is, is not
x = [1, 2, 3]
y = [1, 2, 3]
z = x

print(x is z)      # True (x and z reference the same object)
print(x is y)      # False (x and y are equal but different objects)
print(x is not y)  # True (x and y are different objects)

# Comparing with None should always use 'is'
value = None
print(value is None)       # True (correct way)
print(value == None)       # True (works but not recommended)

# Membership operators: in, not in
fruits = ["apple", "banana", "cherry"]
print("apple" in fruits)        # True
print("mango" in fruits)        # False
print("mango" not in fruits)    # True

# Works with strings too
message = "Hello, World!"
print("World" in message)       # True
print("Python" in message)      # False

# And with dictionaries (checks keys)
person = {"name": "Alice", "age": 25}
print("name" in person)         # True
print("Alice" in person)        # False (not a key)
print("Alice" in person.values()) # True (in values)

# Operator precedence examples
result1 = 10 + 3 * 2       # 16 (not 26) - multiplication before addition
result2 = (10 + 3) * 2     # 26 - parentheses override precedence

# Complex example
x = 5
y = 10
z = 2
result3 = x + y * z / (x - 3)   # 25.0 (evaluated as: 5 + ((10 * 2) / (5 - 3)))

# Logical operators precedence
result4 = True or False and False  # True (and has higher precedence than or)
result5 = (True or False) and False # False (parentheses change the order)

# String multiplication
print("Hello" * 3)    # HelloHelloHello

# List multiplication
print([1, 2] * 3)     # [1, 2, 1, 2, 1, 2]

# String concatenation with +
print("Hello" + " " + "World")  # Hello World

# List concatenation with +
print([1, 2] + [3, 4])          # [1, 2, 3, 4]

# in with strings checks for substring
print("py" in "python")         # True

# Ternary operator (conditional expression)
age = 20
status = "adult" if age >= 18 else "minor"  # "adult"

# The 'walrus' operator := (Python 3.8+)
numbers = [1, 2, 3, 4, 5]
if (n := len(numbers)) > 3:
    print(f"List is long ({n} elements)")  # Assigns and tests in one step

Exercise 1: Predict the Output

# What will the following expressions evaluate to?
print(5 + 3 * 2)
print(5 > 3 and 10 < 20)
print(not True or False)
print(3 in [1, 2, 3, 4] and 5 not in [1, 2, 3, 4])
print(10 * "a" + 5 * "b")

Exercise 2: Fix the Expressions

# Each of these expressions has an error. Fix them:
# print(10 +* 5)
# print(True and False or)
# print(5 < > 3)
# print(10 = 10)
# print(5 in in [1, 2, 3, 4, 5])