Lesson 3b - Booleans

Booleans are one of the simplest data types. It consists entirely of “True” and “False”.

Lesson Objectives

• Learn what booleans are.
• Use boolean operators.
• Compare numerical values.

What’s a Boolean?

Named after George Boole, a boolean is a value that is either true or false. It’s most commonly used in logic. In Python, it’s useful for creating conditional statements and loops, which we’ll talk about in lesson 4.

Creating a Boolean Value

In Python, declaring a boolean value is similar to declaring a number. Rather than using a numerical constant, you need to use True or False.

Make sure True and False are capitalized!

a = True

print(type(a))

<class 'bool'>

Boolean Operators

Just like integers and floats, booleans have their own set of algebraic rules known as Boolean Algebra.

The three most common operations are listed in the table below.

AND

The AND operator results in True if both booleans are already True. Otherwise, it becomes False.

a = True
b = True
c = False

print(a and b)
print(a and c)

True
False

OR

The OR operator results in True if at least one boolean is True. Otherwise, it becomes False.

a = True
b = True
c = False

print(a or c)
print(c or c)

True
False

NOT

The NOT operator reverses the current value. True becomes False, and False becomes True.

a = True
c = False

print(not a)
print(not c)

False
True

Order of Logical Operations

Just like regular algebra, booleans have their own order of operations. The order is listed in the table below. Operations at the top have higher precedence.

Numerical Comparisons

We can also compare the values of expressions to generate a boolean as well.

The six comparison operators are shown in the table below.

print(5 < 8)
print(2 < 1)
print(3 == 3.0)

True
False
True

Key Points / Summary

• A boolean is a True/False value.
• and, or, and not are three boolean operators.
• You can compare numerical values.