Bools — The Full Picture

The idea!

Bool is small. But it's everywhere.

This is your reference. Everything in one place.

Come back here whenever you need a reminder.

What is Bool

is_valid = True
is_banned = False

print(type(is_valid))   # <class 'bool'>

Only two values. Always capitalized.

Comparison Operators

print(10 == 10)   # True  — equal to
print(10 != 9)    # True  — not equal to
print(10 > 5)     # True  — greater than
print(10 < 5)     # False — less than
print(10 >= 10)   # True  — greater than or equal to
print(10 <= 9)    # False — less than or equal to

Comparison operators always return a bool.

Logical Operators

# and — both must be true
print(True and True)    # True
print(True and False)   # False

# or — at least one must be true
print(True or False)    # True
print(False or False)   # False

# not — flips the value
print(not True)    # False
print(not False)   # True

in and not in

name = "RedHornDev"

print("Horn" in name)        # True
print("horn" in name)        # False — case sensitive
print("Horn" not in name)    # False
print("bull" in name.lower()) # True — normalize first

Combining Conditions

age = 20
has_id = True
is_banned = False

print(age > 18 and has_id)              # True
print(age > 18 and has_id and not is_banned)  # True
print(age < 18 or has_id)              # True

Common Mistakes

• True and False are capitalized — always
• = assigns, == compares — never confuse them
• Don't compare a bool to True — just use the bool
• and — ALL must be true. or — ANY can be true
• Avoid not not — rethink the logic instead
• in is case sensitive — normalize before checking

What you should understand now

• bool has only two values — True and False
• Comparison operators always return a bool
• and, or, not combine and modify conditions
• in checks existence — always returns a bool