python - 从 Python 中的 stdin 读取整数

Question

我有下面的代码，我从标准输入中获取整数 n，将其转换为二进制，反转二进制字符串，然后转换回整数并输出。

import sys

def reversebinary():
  n = str(raw_input())
  bin_n = bin(n)[2:]
  revbin = "".join(list(reversed(bin_n)))
  return int(str(revbin),2)

reversebinary()

但是，我收到此错误:

Traceback (most recent call last):   
File "reversebinary.py", line 18, in <module>
  reversebinary()   
File "reversebinary.py", line 14, in reversebinary
   bin_n = bin(n)[2:] 
TypeError: 'str' object cannot be interpreted as an index

我不确定问题是什么。

Answer 1

您正在将字符串传递给 bin() 函数:

>>> bin('10')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'str' object cannot be interpreted as an index

给它一个整数:

>>> bin(10)
'0b1010'

将 raw_input() 结果转换为 int():

n = int(raw_input())

提示:您可以通过给字符串一个负切片步长来轻松反转字符串:

>>> 'forward'[::-1]
'drawrof'

这样你就可以将你的函数简化为:

def reversebinary():
    n = int(raw_input())
    bin_n = bin(n)[2:]
    revbin = bin_n[::-1]
    return int(revbin, 2)

甚至:

def reversebinary():
    n = int(raw_input())
    return int(bin(n)[:1:-1], 2)