Python bool() usage and examples

Python built-in functions

The bool() method uses the standard truth testing process to convert values to boolean values (True or False).

The syntax of bool() is:

bool([value])

bool()参数

传递值给bool()不是必需的。如果不传递值，则bool()返回False。

通常，bool()使用单个参数值。

bool() returns value

bool() returns:

• False ifValueomitted or false

• True ifValuetrue

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, {}

• With __bool__() or __len__() methods returning 0 or False

All other values except these are considered 'true'.

Example: how does bool() work?

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))

When running the program, the output is:

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

Python built-in functions