Python Booleans and Operators

Booleans are the values True and False, and operators are the symbols that work on values.

Boolean Values

A boolean (bool) has only two possible values: True or False. You get one whenever you compare things.

print(10 > 3)
print(10 == 3)
print("ali" == "Ali")

True
False
False

The last one is False because capital and small letters are different.

Truthy and Falsy Values

The bool() function tells you if a value counts as true or false. Empty and zero values are False. Almost everything else is True.

print(bool(0))
print(bool(""))
print(bool([]))
print(bool(None))
print(bool(25))
print(bool("Hi"))

False
False
False
False
True
True

Arithmetic Operators

Assignment Operators

These change a variable using its own value:

points = 10
points += 5    # same as points = points + 5
print(points)
points -= 3
print(points)
points *= 2
print(points)

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Comparison Operators

Logical Operators

and, or and not combine conditions:

age = 20
has_cnic = True
print(age >= 18 and has_cnic)
print(age < 18 or has_cnic)
print(not has_cnic)

True
True
False

• and is True only if both sides are True
• or is True if at least one side is True
• not flips True to False and False to True

Membership and Identity Operators

in and not in check if a value is inside a collection. is checks if two names point to the very same object.

fruits = ["mango", "banana", "apple"]
print("mango" in fruits)
print("grapes" not in fruits)

x = None
print(x is None)

True
True
True

Use is mainly to check for None. For normal comparisons, use ==.

Operator Precedence

Python does some operators before others, like in school maths. ** comes first, then * / // %, then + -, then comparisons, then not, and, or. Use brackets to make your meaning clear:

print(2 + 3 * 4)
print((2 + 3) * 4)

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Exercise