###### tags: `leetcode` `python3`
cited by =
https://hackmd.io/2KBqq0S0TqKvtqUHUhyyTg?edit
# Learn `bit_length()`

## Only named int can use it.

Python 3.6.8 (default, Jan 14 2019, 11:02:34) 
[GCC 8.0.1 20180414 (experimental) [trunk revision 259383]] on linux
Type "help", "copyright", "credits" or "license" for more information.


>>> 1.length()
  File "<stdin>", line 1
    1.length()
           ^
SyntaxError: invalid syntax

>>> a=1; a.bit_length()
1

>>> a='1'; a.bit_length()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'str' object has no attribute 'bit_length'

>>> a=1.1; a.bit_length()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'float' object has no attribute 'bit_length'

>>> a=[]; a.bit_length()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'list' object has no attribute 'bit_length'

>>> a=(1); a.bit_length()
1

>>> a=(1,1); a.bit_length()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'bit_length'

>>> a={1}; a.bit_length()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'set' object has no attribute 'bit_length'
>>> 

>>> a=map(str,[1,2]); a.bit_length()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'map' object has no attribute 'bit_length'

>>> a=list(map(str,[1,2])); a.bit_length()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'list' object has no attribute 'bit_length'