Python の組み込み bin 関数の詳細な紹介

>>> b = bin(3) 
>>> b
'0b11'
>>> type(b) #获取b的类型
<class &#39;str&#39;>

>>> class A:
    pass

>>> a = A()
>>> bin(a) 
Traceback (most recent call last):
  File "<pyshell#15>", line 1, in <module>
    bin(a)
TypeError: &#39;A&#39; object cannot be interpreted as an integer

>>> class B:
    def __index__(self):
        return "3"

>>> b = B()
>>> bin(b)
Traceback (most recent call last):
  File "<pyshell#21>", line 1, in <module>
    bin(b)
TypeError: __index__ returned non-int (type str)

>>> class C:
    def __index__(self):
        return 3

>>> c = C()
>>> bin(c)
'0b11'