Python Logical Operators

Logical operators are used to combine or modify conditions. They are particularly useful when a program needs to evaluate more than one condition at the same time.

Python provides three main logical operators:

The and operator returns True only when both conditions are true.

print(True and True)
print(True and False)
print(False and True)
print(False and False)

True
False
False
False

Think of and as saying: "Both conditions must be satisfied."

age = 25

print(age >= 18 and age <= 60)

True

Both comparisons are true, so the complete expression is true.

The or operator returns True when at least one condition is true.

print(True or True)
print(True or False)
print(False or True)
print(False or False)

True
True
True
False

Think of or as saying: "At least one condition must be satisfied."

day = "Saturday"

print(day == "Saturday" or day == "Sunday")

True

The not operator reverses a Boolean result.

print(not True)
print(not False)

False
True

It can also be applied to a comparison.

age = 15

print(not age >= 18)

True

The comparison age >= 18 is False. Applying not changes it to True.

A truth table shows the result of a logical operation for every possible combination of Boolean values.

and Truth Table

or Truth Table

not Truth Table

Suppose a website requires a user to be at least 18 years old and have a valid membership.

age = 25
member = True

print(age >= 18 and member == True)

True

If either condition becomes false, the complete and expression becomes false.

age = 16
member = True

print(age >= 18 and member == True)

False

Suppose a customer can receive a discount if they are either a premium member or their purchase exceeds a certain amount.

premium_member = False
purchase = 8000

print(premium_member == True or purchase >= 5000)

True

The first condition is false, but the second condition is true. Because or needs only one true condition, the final result is True.

The not operator is useful when you want to check the opposite of a condition.

logged_in = False

print(not logged_in)

True

Since logged_in is false, not logged_in becomes true.

You can use more than one logical operator in the same expression.

age = 25
student = True

result = age >= 18 and student == True

print(result)

True

More complex conditions can also use parentheses to make the intended logic clear.

age = 25
student = True
employee = False

result = age >= 18 and (student == True or employee == True)

print(result)

True

When multiple logical operators appear in the same expression, Python follows a specific order.

The logical precedence order is:

1. not
2. and
3. or

result = True or False and False

print(result)

True

Python evaluates False and False first, producing False. It then evaluates True or False, producing True.

One of the most common patterns in Python is to combine comparison operators with logical operators.

age = 30
salary = 75000

eligible = age >= 18 and salary >= 50000

print(eligible)

True

This pattern will become extremely important when you start writing if statements.

Boolean variables can be combined directly with logical operators.

has_id = True
has_ticket = True

allowed = has_id and has_ticket

print(allowed)

True

A cleaner Python style is often to use Boolean variables directly instead of writing comparisons such as has_id == True.

has_id = True
has_ticket = True

allowed = has_id and has_ticket

print(allowed)

Online Store Eligibility

Imagine an online store that gives free delivery when a customer is either a premium member or spends at least Rs. 5,000.

premium = False
cart_total = 6500

free_delivery = premium or cart_total >= 5000

print(free_delivery)

True

Student Eligibility

A student may qualify for a program if they meet both an age requirement and a marks requirement.

age = 21
marks = 78

eligible = age >= 18 and marks >= 60

print(eligible)

True

Login Verification

A system may require both a valid username and password.

username_correct = True
password_correct = True

login_successful = username_correct and password_correct

print(login_successful)

True

1. Confusing and with or

Remember:

• and requires every condition to be true.
• or requires at least one condition to be true.

2. Using && instead of and

Python uses English-style logical keywords.

age >= 18 and age <= 60

3. Forgetting parentheses in complex logic

Although Python has defined precedence rules, parentheses often make complicated expressions much easier to understand.

age >= 18 and (student or employee)

4. Comparing Boolean variables unnecessarily

Instead of:

if logged_in == True:

You can usually write:

if logged_in:

Try each exercise yourself before looking for a solution.

Build a program that asks the user for their age, marks, and student status.

The student should be considered eligible when:

• Their age is at least 18.
• Their marks are at least 60.
• They are a registered student.

age = int(input("Enter your age: "))
marks = int(input("Enter your marks: "))

student = input("Are you a registered student? ")

is_student = student.lower() == "yes"

eligible = age >= 18 and marks >= 60 and is_student

print("Eligible:", eligible)

Logical operators allow Python programs to combine multiple conditions and make more sophisticated decisions.

In the next lesson, we will continue with another important group of operators: Membership and Identity Operators.