Python Logical Conditions Examples

Short, runnable programs that show python logical conditions in action. Read the explanation, press Run, then change the code and try your own ideas. New to the topic? Start with the Python Logical Conditions lesson.

1Build a rule from named pieces

Giving each part of the rule its own name keeps the final condition short, and lets you print any part to see why a decision came out the way it did.

Build a rule from named pieces

age = 13
has_ticket = True
with_adult = True
film_rating = 15

old_enough = age >= film_rating
has_permission = old_enough or with_adult
can_watch = has_ticket and has_permission

print("Old enough:", old_enough)
print("Has permission:", has_permission)
print("Can watch:", can_watch)

Expected outputOld enough: False
Has permission: True
Can watch: True

2Short-circuiting as a safety guard

Indexing an empty string with [0] would raise an IndexError. Checking the length first with and means the risky half is only evaluated when it is safe.

Short-circuiting as a safety guard

username = ""
if len(username) > 0 and username[0] == "A":
    print("Starts with A")
else:
    print("Empty, or does not start with A")

username = "Asha"
if len(username) > 0 and username[0] == "A":
    print("Starts with A")
else:
    print("Empty, or does not start with A")

Expected outputEmpty, or does not start with A
Starts with A

3Flipping a whole condition with not

not (A or B) is the same as not A and not B. When you negate a combined condition, you flip each comparison and swap or for and (and the other way round). Two equivalent ways to write it:

Flipping a whole condition with not

temperature = 31
humidity = 80

too_uncomfortable = temperature > 30 or humidity > 70
comfortable = not (temperature > 30 or humidity > 70)
comfortable_other_way = temperature <= 30 and humidity <= 70

print(too_uncomfortable)
print(comfortable)
print(comfortable_other_way)

Expected outputTrue
False
False

4in and not in with lists, tuples and text

The same operator works on lists, tuples and strings. With text, in checks for a smaller piece of text anywhere inside it.

in and not in with lists, tuples and text

roles = ["editor", "viewer"]
weekend = ("Sat", "Sun")
message = "Your order has shipped"

print("admin" in roles)
print("Mon" in weekend)
print("shipped" in message)
print("refund" not in message)
print("ship" in message and "refund" not in message)

Expected outputFalse
False
True
True
True

5or as a fallback value

or returns the first operand that counts as True, or the last operand if none do. That makes entered or default a compact way to say "use this unless it is empty".

or as a fallback value

default_city = "Pune"
entered_city = ""
city = entered_city or default_city
print(city)

entered_city = "Oslo"
city = entered_city or default_city
print(city)

print(0 or 5, 3 or 5)

Expected outputPune
Oslo
5 3

Practise next

Python Logical Conditions exercises → Back to the lesson

Python Operators examples Python Shorthand If (Ternary) examples Python Truthy and Falsy Values examples