Logical Operators

Combine conditions with and, or, not, the glue of real decisions

You can compare two values with ==, <, > etc. But what if you need to check *two conditions at once*? That's where logical operators come in.
There are three: and, or, not.

and, or, notpython

age = 25
has_ticket = True

# and, both must be True
if age >= 18 and has_ticket:
    print("You can enter")

# or, at least one must be True
is_admin = False
is_vip = True
if is_admin or is_vip:
    print("Access granted")

# not, flips True to False and vice versa
is_banned = False
if not is_banned:
    print("Welcome!")

Truth tables, exactly when each returns True:
and, True only when BOTH sides are True:

True and True → True

True and False → False

False and True → False

False and False → False

or, True when AT LEAST ONE side is True:

True or True → True

True or False → True

False or True → True

False or False → False

not, flips the boolean:

not True → False

not False → True

🤔Quick Check

What does True and False or True evaluate to?

Short-circuit evaluation, Python is lazy (in a good way)
With and: if the left side is False, Python doesn't even check the right side (can't be True anyway).
With or: if the left side is True, Python skips the right side (already True).
This matters when the right side could cause an error:

Short-circuit in actionpython

# Safe, checks length first before accessing index
text = ""
if len(text) > 0 and text[0] == "H":
    print("Starts with H")
else:
    print("Empty or doesn't start with H")

# Combining comparisons
score = 75
if 60 <= score <= 100:   # Python allows chaining!
    print("Pass")

Common mistake: Don't write if x == 1 or 2:, this always evaluates to True because 2 is truthy. Write if x == 1 or x == 2: instead.

🤔Quick Check

Which correctly checks if a number is between 1 and 10 (inclusive)?

Practice Exercises

0/3 solved

Exercise 1 of 3easy

⏱ 00:00

Age & ID Check

A club requires guests to be 18+ AND have a valid ID.
Given: age = 20, has_id = TruePrint "Allowed" if both conditions are met, otherwise print "Denied".

solution.py

1 / 3

Exercise 2 of 3easy

⏱ 00:00

Login Validator

A login fails if the username is empty OR the password is shorter than 8 characters.
Given: username = "alice", password = "abc"Print "Login failed: weak password" if the password < 8 chars, "Login failed: no username" if username is empty, otherwise "Login OK".

solution.py

2 / 3

Exercise 3 of 3easyTrace

⏱ 00:00

Fix the Logic Bug

The code below should print "Discount applied" if the user is a student OR a senior (age 65+). But it has a logic bug, fix it.

solution.py

3 / 3

Solve all 3 exercises to unlock completion

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