python function - bool([x])

bool([x])

English description: Convert a value to a Boolean, using the standard truth testing procedure. If x is false or omitted, this returns False; otherwise it returns True. bool is also a class, which is a subclass of int. Class bool cannot be subclassed further. Its only instances are False and True.

New in version 2.2.1.

Changed in version 2.3: If no argument is given, this function returns False.

Chinese description: Convert x to Boolean type. If x is default, return False, bool is also a subclass of int;

Parameter x: any object or default; everyone noticed: [x] is used here , indicating that the x parameter is optional. If no parameters are given, False will be returned.

Version: A new function introduced in python 2.2.1. After python2.3, it returns False if no parameters are passed.

Note: This function can also be used normally in python3

Example:

>>> bool(0)
False
>>> bool("abc")
True
>>> bool("")
False
>>> bool([])
False
>>> bool()
False
>>> issubclass(bool, int) #bool是一个subclass int
True