Boolean Values In Python

 

True and False are two Boolean values.

 Any expression using relational operators give one of two answers, True or False.

 Example

print(10 > 3)

print(10 == 3)

print(10 < 2)

When you run a condition in an if statement, Python returns True or False: 

Print a message based on whether the condition is True or False:

 a = 100

b = 33

 if b > a:

  print("b is greater than a")

else:

  print("b is not greater than a")

 

Evaluate Values and Variables

 

The bool() function allows you to evaluate any value, and give you True or False in return,

 

Example

Evaluate a string and a number:

 

print(bool("Hello"))

print(bool(15))

Example

Evaluate two variables:

 

x = "Hello"

y = 15

 

print(bool(x))

print(bool(y))

Most Values are True

Almost any value is evaluated to True if it has some sort of content.

 

Any string is True, except empty strings. Similarly any number is True, except 0.

 

Any list, tuple, set, and dictionary are True, except empty ones.

 

Example

The following will return True:

 

bool("abc")

bool(123)

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

Some Values are False

In fact, there are not many values that evaluate to False, except empty values, such as (), [], {}, "", the number 0, and the value None. And of course the value False evaluates to False.

 

Example

The following will return False:

 

bool(False)

bool(None)

bool(0)

bool("")

bool(())

bool([])

bool({})