Python built-in functions (5) -- bin, python built-in function bin

Python built-in functions (5) -- bin, python built-in function bin

English document:

bin(X)

Convert an integer number to a binary string. The result is a valid Python expression. IfXIs not a PythonintObject, it has to define__index__()Method that returns an integer.

Note:

1. convert an integer to a binary string

>>> B = bin (3) >>> B '0b11 '>>> type (B) # obtain the type of B <class 'str'>

2. If the x parameter is not an integer, x must define a _ index _ () method, and the return value of the method must be an integer.

2.1 if the object is not an integer, an error is returned.

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

2.2 If the _ index _ method is defined but the return value is not an integer, an error is returned.

>>> 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)

2.3 The object defines the _ index _ method and the return value is an integer. Convert the return value of the _ index _ method to a binary string.

>>> class C:    def __index__(self):        return 3>>> c = C()>>> bin(c)'0b11'