Booleans

Booleans

In this tutorial, we'll represent yes/no values with True and False.

A boolean is a value that is either True or False.

is_raining = True
is_logged_in = False

Booleans are used when your program needs to make decisions.

Comparisons Create Booleans

Most booleans come from comparisons:

age = 17

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

Output:

False
True

Python checks the comparison and gives a boolean result.

Using Booleans With if

Booleans are often used in if statements:

is_member = True

if is_member:
    print("Discount applied")
else:
    print("No discount")

The if branch runs when the condition is True.

Boolean Operators

Use and, or, and not to combine boolean logic:

age = 20
has_ticket = True

print(age >= 18 and has_ticket)
print(age >= 18 or has_ticket)
print(not has_ticket)

and requires both sides to be true. or requires at least one side to be true. not flips the value.

Truthy and Falsy

Some non-boolean values behave like booleans in conditions:

name = ""

if name:
    print("Name entered")
else:
    print("No name yet")

An empty string is falsy. A non-empty string is truthy.

Common Mistake

Booleans start with capital letters:

is_ready = True   # correct
is_done = false   # wrong

Python uses True and False, not true and false.

Practice

Create variables for age and has_permission. Print whether the person is allowed in if they are at least 13 and have permission.