Python Boolean Values

In Python, Boolean values represent one of two possible states: True or False. These values are fundamental when working with logical operations and conditional statements.

Understanding Boolean Expressions

Boolean expressions evaluate to either True or False. These expressions are often used in conditional statements to control program flow.

print(10 > 9)
print(10 == 9)
print(10 < 9)

Booleans in Conditional Statements

Python uses Boolean expressions to evaluate conditions within if statements:

a = 200
b = 33

if b > a:
    print("b is greater than a")
else:
    print("b is not greater than a")

Evaluating Values and Variables

The built-in bool() function converts a value to a Boolean. Any object or variable can be evaluated to determine its truthiness.

print(bool("Hello"))
print(bool(15))

x = "Hello"
y = 15

print(bool(x))
print(bool(y))

Truthy Values in Python

In Python, most non-empty values evaluate to True. This includes non-empty strings, non-zero numbers, and non-empty containers such as lists or dictionaries.

bool("abc")
bool(123)
bool(["apple", "cherry", "banana"])

Falsy Values in Python

Conversely, certain values evaluate to False. These include empty sequences or collections, the number zero, None, and of course the Boolean value False itself.

bool(False)
bool(None)
bool(0)
bool("")
bool(())
bool([])
bool({})

Additionally, if a custom object defines a __len__ method that returns zero, it is considered False when evaluated.

class myclass():
    def __len__(self):
        return 0

myobj = myclass()
print(bool(myobj))

Boolean Values Returned from Functions

Functions in Python can return Boolean values. This is particularly useful for making decisions in your code.

def myFunction():
    return True

print(myFunction())

Conditional logic can then be applied based on the return value:

if myFunction():
    print("YES!")
else:
    print("NO!")

Built-in Functions Returning Booleans

Python includes many built-in functions that return Boolean results. One such function is isinstance(), which checks if a variable belongs to a specific data type.

x = 200
print(isinstance(x, int))

This form of type-checking is essential in writing reliable and error-free Python programs.

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