🧠 Python Logical Operators: Complete Guide

What are Logical Operators?

Logical operators are used to combine conditional statements. They work with boolean values (True and False) and return a boolean result. Python provides three logical operators: and, or, and not.

Think of logical operators as question combiners. Instead of asking one question at a time, you can combine multiple questions: "Is the user logged in AND has permission?" or "Is the user an admin OR a moderator?"

1. AND Operator (and)

The AND operator (and) returns True only if both conditions are True. If any condition is False, the result is False.

# AND Operator Examples
print(True and True)    # Output: True
print(True and False)   # Output: False
print(False and True)   # Output: False
print(False and False)  # Output: False

# With variables
age = 25
has_license = True
can_drive = age >= 18 and has_license
print(can_drive)        # Output: True

# Short-circuit evaluation
x = 5
print(x > 0 and x < 10)  # Output: True

2. OR Operator (or)

The OR operator (or) returns True if at least one condition is True. It only returns False when both conditions are False.

# OR Operator Examples
print(True or True)     # Output: True
print(True or False)    # Output: True
print(False or True)    # Output: True
print(False or False)   # Output: False

# With variables
has_cash = False
has_card = True
can_pay = has_cash or has_card
print(can_pay)          # Output: True

# Short-circuit evaluation
x = 5
print(x < 0 or x > 0)   # Output: True

3. NOT Operator (not)

The NOT operator (not) reverses the boolean value. It returns True if the condition is False, and False if the condition is True.

# NOT Operator Examples
print(not True)         # Output: False
print(not False)        # Output: True

# With variables
is_weekend = False
is_workday = not is_weekend
print(is_workday)       # Output: True

# Combining with other operators
age = 15
can_vote = age >= 18
cannot_vote = not can_vote
print(cannot_vote)      # Output: True

4. Truth Tables

Truth tables help visualize how logical operators work. Here are the truth tables for AND, OR, and NOT:

AND (and)

OR (or)

NOT (not)

5. Operator Precedence

When combining multiple logical operators, Python follows a specific order of evaluation:

Precedence (highest to lowest):

1. not        (highest)
2. and
3. or         (lowest)

# Examples
result = True or False and False
# and is evaluated first: False and False = False
# then or: True or False = True
print(result)  # Output: True

# Use parentheses for clarity
result = (True or False) and False
print(result)  # Output: False

6. Real-World Examples

# User Authentication Example
is_logged_in = True
has_permission = True
is_admin = False

# Check if user can access dashboard
can_access = is_logged_in and (has_permission or is_admin)
print(f"Can access dashboard: {can_access}")  # Output: True

# Grade Eligibility Example
score = 85
attendance = 90
has_passed = score >= 75 and attendance >= 80
print(f"Student passed: {has_passed}")  # Output: True

# Discount Eligibility Example
total = 150
is_member = True
has_coupon = False

# Get discount if total > 100 AND (is_member OR has_coupon)
eligible = total > 100 and (is_member or has_coupon)
print(f"Eligible for discount: {eligible}")  # Output: True

7. Common Mistakes to Avoid

# WRONG
if x > 0 & x < 10:  # & is bitwise AND, not logical AND

# CORRECT
if x > 0 and x < 10:  # Use 'and' for logical AND

# WRONG (unclear precedence)
if not x > 5 or y < 10:
    pass

# CORRECT (using parentheses)
if not (x > 5 or y < 10):
    pass

# Truthy and Falsy values
print(0 and 5)     # Output: 0 (first Falsy value)
print(5 and 0)     # Output: 0 (second Falsy value)
print(5 and 10)    # Output: 10 (last value)

# Always use explicit comparisons for clarity
if x is not None and x > 0:
    pass

Try It Yourself!

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📚 Where to Go From Here

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