在python中，任何对象都可以判断其真假值：true，false
在if或while条件判断中，下面的情况值为false：
1.none
2.flase
3.数值为0的情况，如：0,0.0,0j
4.所有空序列，如：'',(),[]
5.所有空mapping，如：{}
6.instances of user-defined classes, if the class defines a __bool__() or __len__() method,
   when that method returns the integer zero or bool value false.
all other values are considered true — so objects of many types are always true.
在运算操作和内建函数返回boolean结果0或者flase表示false
1或true表示true
python中的boolean运算如下：
print('x or y -> if x is false,then y, else x ') x, y = 2, 0 print('{} or {} = {}'.format(x, y, x or y)) x1, y1 = 0, 10 print('{} or {} = {}'.format(x1, y1, x1 or y1)) x2, y2 = 0, 0 print('{} or {} = {}'.format(x2, y2, x2 or y2)) print('#' * 50) print('x and y -> if x is false,then x, else y ') print('{} and {} = {}'.format(x, y, x and y)) x1, y1 = 0, 10 print('{} and {} = {}'.format(x1, y1, x1 and y1)) x2, y2 = 0, 0 print('{} and {} = {}'.format(x2, y2, x2 and y2)) print('#' * 50) print('not x -> if x is false,then true,else false ') x = 2 print('not {} = {}'.format(x, not x)) x = 0 print('not {} = {}'.format(x, not x))
运行结果：
>>>
x or y -> if x is false,then y, else x
or 0 = 2
or 10 = 10
or 0 = 0
##################################################
x and y -> if x is false,then x, else y
and 0 = 0
and 10 = 0
and 0 = 0
##################################################
not x -> if x is false,then true,else false
not 2 = false
not 0 = true
>>>