bool

1. Boolean Values

Meaning: Represents true or false in judgments, generally used in conditional tests.

a = True
print(a)
print(10 < 5)
print(10 > 8)

# output
True
False
True

image-20240207073308404

• All non-empty values are considered True.
• All empty sequences, empty numbers are considered False.

2. Logical Operators

Logical operators: Used to check if two or more conditions are satisfied.

Logical operators exist only in booleans.

Logical Operator	Description
and ("logical and")	Returns True if both operands are True.
or ("logical or")	Returns True if at least one of the operands is True.
not ("logical not")	Used to reverse the state of the operand.

exp	bool	value	Return value === print(exp)
3 and 5	True and True	True	5 *Evaluates from left to right, returns 5 when it reaches True (both need to be True)
3 or 5	True or True	True	3 *Only needs one True, so stops at 3
0 or 5	False or True	True	5 *Stops at 5 to satisfy the condition
3 and not 5	True and False	False	False
0 and 5	False and True	False	0 *0 and False are equivalent

s1 = {False, 0}
s2 = {0, False}
print(s1, s2)

# output
{False} {0}  # The set automatically removes duplicates - 0 and False are considered equivalent

In [5]: True and False or True 
Out[5]: True
# Evaluates the right side of and first, from right to left

In [6]: False or False or not False
Out[6]: True

3. Expression Application — Conditional Testing

• Check if the current variable is equal to a specific value.
• Compare the size of numbers.
• Check if a specific value is in a sequence.

3.1 Multiple Conditions Checking

Use and to check multiple conditions.

age1 = 17
age2 = 18
print(age1 >= 18 and age2 >=18)
print(age1 >= 15 and age2 >=18)

# output
False
True

Use or to check multiple conditions.

age1 = 17
age2 = 18
print(age1 >= 18 or age2 >=18)
print(age1 >= 15 or age2 >=18)

# output
True
True

image-20240207073333734