Python Operators

Introduction

Operators are special symbols in Python that carry out arithmetic or logical computation. The value that the operator operates on is called the operand. For example, in the expression 2 + 3, + is the operator and 2 and 3 are the operands.

Python provides a variety of operators grouped into several categories. Understanding these operators is crucial for writing efficient Python code and implementing logic in your programs.

Arithmetic Operators

Arithmetic operators are used to perform mathematical operations like addition, subtraction, multiplication, etc.

Operator	Description	Example
+	Addition	x + y
-	Subtraction	x - y
*	Multiplication	x * y
/	Division	x / y
%	Modulus (remainder)	x % y
**	Exponentiation	x ** y
//	Floor division	x // y

Examples

python

a = 10
b = 3

# Addition
print(f"a + b = {a + b}")  # 13

# Subtraction
print(f"a - b = {a - b}")  # 7

# Multiplication
print(f"a * b = {a * b}")  # 30

# Division
print(f"a / b = {a / b}")  # 3.3333333333333335

# Modulus
print(f"a % b = {a % b}")  # 1

# Exponentiation
print(f"a ** b = {a ** b}")  # 1000

# Floor Division
print(f"a // b = {a // b}")  # 3

Assignment Operators

Assignment operators are used to assign values to variables.

Operator	Description	Example	Equivalent to
=	Assign value	x = 5	x = 5
+=	Add and assign	x += 5	x = x + 5
-=	Subtract and assign	x -= 5	x = x - 5
*=	Multiply and assign	x *= 5	x = x * 5
/=	Divide and assign	x /= 5	x = x / 5
%=	Modulus and assign	x %= 5	x = x % 5
**=	Exponentiate and assign	x **= 5	x = x ** 5
//=	Floor divide and assign	x //= 5	x = x // 5

Examples

python

x = 10

# Add and assign
x += 5
print(f"After x += 5: {x}")  # 15

# Reset x
x = 10

# Subtract and assign
x -= 3
print(f"After x -= 3: {x}")  # 7

# Reset x
x = 10

# Multiply and assign
x *= 2
print(f"After x *= 2: {x}")  # 20

Comparison Operators

Comparison operators are used to compare values. They return either True or False according to the condition.

Operator	Description	Example
==	Equal to	x == y
!=	Not equal to	x != y
>	Greater than	x > y
<	Less than	x < y
>=	Greater than or equal to	x >= y
<=	Less than or equal to	x <= y

Examples

python

a = 10
b = 5
c = 10

print(f"a == b: {a == b}")  # False
print(f"a != b: {a != b}")  # True
print(f"a > b: {a > b}")    # True
print(f"a < b: {a < b}")    # False
print(f"a >= c: {a >= c}")  # True
print(f"a <= c: {a <= c}")  # True

Logical Operators

Logical operators are used to combine conditional statements.

Operator	Description	Example
and	Returns True if both statements are true	x < 5 and x < 10
or	Returns True if one of the statements is true	x < 5 or x < 4
not	Reverse the result, returns False if the result is true	not(x < 5 and x < 10)

Examples

python

x = 5

print(f"x > 3 and x < 10: {x > 3 and x < 10}")  # True
print(f"x > 8 or x < 4: {x > 8 or x < 4}")      # False
print(f"not(x > 8): {not(x > 8)}")              # True

Identity Operators

Identity operators are used to compare the objects, not if they are equal, but if they are actually the same object with the same memory location.

Operator	Description	Example
is	Returns True if both variables reference the same object	x is y
is not	Returns True if both variables do not reference the same object	x is not y

Examples

python

a = [1, 2, 3]
b = [1, 2, 3]
c = a

print(f"a is b: {a is b}")      # False, they are different objects
print(f"a is c: {a is c}")      # True, they reference the same object
print(f"a is not b: {a is not b}")  # True

Membership Operators

Membership operators are used to test if a sequence is presented in an object.

Operator	Description	Example
in	Returns True if a sequence with the specified value is present in the object	x in y
not in	Returns True if a sequence with the specified value is not present in the object	x not in y

Examples

python

fruits = ["apple", "banana", "cherry"]

print(f"'apple' in fruits: {'apple' in fruits}")           # True
print(f"'orange' in fruits: {'orange' in fruits}")         # False
print(f"'orange' not in fruits: {'orange' not in fruits}") # True

Bitwise Operators

Bitwise operators are used to compare binary numbers.

Operator	Description	Example
&	AND	x & y
|	OR	x | y
^	XOR	x ^ y
~	NOT	~x
<<	Zero fill left shift	x << n
>>	Signed right shift	x >> n

Examples

python

a = 10  # binary: 1010
b = 7   # binary: 0111

# Bitwise AND
print(f"a & b: {a & b}")    # 2 (binary: 0010)

# Bitwise OR
print(f"a | b: {a | b}")    # 15 (binary: 1111)

# Bitwise XOR
print(f"a ^ b: {a ^ b}")    # 13 (binary: 1101)

# Bitwise NOT
print(f"~a: {~a}")          # -11 (binary: -1011)

# Left Shift
print(f"a << 2: {a << 2}")  # 40 (binary: 101000)

# Right Shift
print(f"a >> 2: {a >> 2}")  # 2 (binary: 10)

Operator Precedence

Operator precedence determines the order in which operators are evaluated in an expression. Operators with higher precedence are evaluated before operators with lower precedence.

Here's a simplified list of Python operator precedence (from highest to lowest):

1. ** (Exponentiation)
2. ~, +, - (Bitwise NOT, Unary plus and minus)
3. *, /, //, % (Multiplication, Division, Floor division, Modulus)
4. +, - (Addition, Subtraction)
5. <<, >> (Bitwise shift operators)
6. & (Bitwise AND)
7. ^ (Bitwise XOR)
8. | (Bitwise OR)
9. ==, !=, >, >=, <, <=, is, is not, in, not in (Comparisons, Identity, Membership)
10. not (Logical NOT)
11. and (Logical AND)
12. or (Logical OR)

Example

python

result = 10 + 3 * 2 ** 2
print(f"10 + 3 * 2 ** 2 = {result}")  # 22

# Explanation:
# 1. 2 ** 2 = 4 (Exponentiation has highest precedence)
# 2. 3 * 4 = 12 (Multiplication is next)
# 3. 10 + 12 = 22 (Addition is last)

Real-World Applications

1. Calculating Total Cost with Discount

python

def calculate_total(price, quantity, discount_rate=0):
    """Calculate the total cost after applying a discount."""
    subtotal = price * quantity
    discount = subtotal * discount_rate
    total = subtotal - discount
    return total

# Regular purchase
regular_purchase = calculate_total(19.99, 3)
print(f"Regular purchase total: ${regular_purchase:.2f}")  # $59.97

# Purchase with 15% discount
discounted_purchase = calculate_total(19.99, 3, 0.15)
print(f"Discounted purchase total: ${discounted_purchase:.2f}")  # $50.97

2. User Access Control

python

def check_user_access(user_role, is_admin, is_active):
    """Check if the user has access to the admin panel."""
    has_access = (user_role == "admin" or is_admin) and is_active
    return has_access

# Different user scenarios
print(f"Admin user, active: {check_user_access('admin', False, True)}")        # True
print(f"Regular user with admin rights, active: {check_user_access('user', True, True)}")  # True
print(f"Admin user, inactive: {check_user_access('admin', False, False)}")     # False
print(f"Regular user, active: {check_user_access('user', False, True)}")       # False

3. List Filtering with Comprehension

python

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# Create a list of even numbers using operator in a comprehension
even_numbers = [num for num in numbers if num % 2 == 0]
print(f"Even numbers: {even_numbers}")  # [2, 4, 6, 8, 10]

# Create a list of squares for numbers greater than 5
squares_gt5 = [num**2 for num in numbers if num > 5]
print(f"Squares of numbers > 5: {squares_gt5}")  # [36, 49, 64, 81, 100]

Summary

In this module, we covered the different types of operators in Python:

• Arithmetic Operators: Used for mathematical operations
• Assignment Operators: Used to assign values to variables
• Comparison Operators: Used to compare values
• Logical Operators: Used to combine conditional statements
• Identity Operators: Used to check if objects are the same
• Membership Operators: Used to check if a value exists in a sequence
• Bitwise Operators: Used to perform operations on binary representations of numbers

Understanding operators is fundamental to programming in Python. They allow you to manipulate data, control program flow, and implement complex logic in your applications.

Exercises

1. Write a program to calculate the area and perimeter of a rectangle using arithmetic operators.
2. Create a temperature converter that converts Celsius to Fahrenheit and vice versa using the formula F = C * 9/5 + 32.
3. Write a program that checks if a number is even and positive using logical operators.
4. Create a simple calculator that can perform addition, subtraction, multiplication, and division based on user input.
5. Write a program that checks if an element exists in a list and prints an appropriate message using membership operators.

Additional Resources

• Python Documentation on Operators
• Real Python - Python Operators: A Detailed Breakdown
• W3Schools - Python Operators