The boolean Type in Python

In Python, the bool type is used to represent the logical values of truth and falsehood. bool objects are instances of the predefined constants True and False.

These values are fundamental to Boolean logic in programming and are used in conditional expressions and logical operations.

Boolean values are declared using the keywords True and False:

true_value = True

false_value = False

Operations with Boolean Values

Python supports basic logical operations with boolean values, such as and, or, and not:

and Operator

The and operator returns True if both operands are True, otherwise it returns False.

and_result = True and False
print(and_result)  # Output: False

or Operator

The or operator returns True if at least one of the operands is True, otherwise it returns False.

or_result = True or False
print(or_result)  # Output: True

not Operator

The not operator returns True if its operand is False, and False if its operand is True, inverting the boolean value.

not_result = not True
print(not_result)  # Output: False

Comparisons and Conditions

In Python, logical expressions return boolean values. For example:

result = 10 > 5
print(result)  # Output: True

Boolean values are frequently used in comparisons and conditions to control the flow of the program:

number = 10
is_greater_than_five = number > 5
if is_greater_than_five:
    print("The number is greater than five")
else:
    print("The number is not greater than five")

Short-Circuit Evaluation

Python uses short-circuit evaluation to optimize logical operations.

• In an and expression, if the first operand is False, the second is not evaluated.
• In an or expression, if the first operand is True, the second is not evaluated.

# Short-circuit evaluation with `and`
result = False and function_that_is_not_evaluated()

# Short-circuit evaluation with `or`
result = True or function_that_is_not_evaluated()

Type Conversion

It is possible to convert other data types to boolean using the bool() function:

# Conversion of numbers
number = 42
boolean_value = bool(number)
print(boolean_value)  # Output: True (any non-zero number is True)

# Conversion of empty strings
empty_string = ""
boolean_value = bool(empty_string)
print(boolean_value)  # Output: False (an empty string is False)