Python bool()

The bool() function converts a value to Boolean (True or False) using the standard truth testing procedure.

The syntax of bool() is:

bool([value])

1. bool() parameters

It’s not mandatory to pass a value to bool(). If you do not pass a value, bool() returns False.

In general use, bool() takes a single parameter value.

2. Return Value from bool()

bool() returns:

• False if the value is omitted or false
• True if the value is true

The following values are considered false in Python:

• None
• False
• Zero of any numeric type. For example, 0, 0.0, 0j
• Empty sequence. For example, (), [], ''.
• Empty mapping. For example, {}
• objects of Classes which has __bool__() or __len()__ method which returns 0 or False

All other values except these values are considered true.

3. Example: How bool() works?

test = []
print(test,'is',bool(test))

test = [0]
print(test,'is',bool(test))

test = 0.0
print(test,'is',bool(test))

test = None
print(test,'is',bool(test))

test = True
print(test,'is',bool(test))

test = 'Easy string'
print(test,'is',bool(test))

Output

[] is False
[0] is True
0.0 is False
None is False
True is True
Easy string is True