Python学习笔记(函数)

None作为布尔值和False是一样的，如何区分None和False?

thing = None

if thing:
    print("It's some thing.")
else:
    print("It's no thing.")


if thing is None:
    print("It's nothing")
else:
    print("It's something")

# 你需要把None和不含任何值的空数据结构区分开来。0值的整型/浮点型、
# 空字符串('')、空列表([])、空元组((,))、空字典({})、
# 空集合(set())都等价于False，但是不等于None。


def is_none(thing):
    if thing is None:
        print("It's None")
    elif thing:
        print("It's True")
    else:
        print("It's False")

is_none(None)
is_none(True)
is_none(False)
is_none(0)
is_none(0.0)
is_none(())
is_none([])
is_none({})
is_none(set())

运行结果:

It's no thing.
It's nothing
It's None
It's True
It's False
It's False
It's False
It's False
It's False
It's False
It's False