如何理解我-i在python中? python中的位操作 [英] how to understand i & -i in python? bit manipulation in python

问题描述

我找到&" python中的意思是基于位表达式的和"运算.最近，我发现了一个非常聪明的代码，其中一行类似于'i& -i'，其中i是整数.如何理解'i& -一世'.另外，python如何处理负整数'-i'进行位操作?

I find '&' in python means 'and' operation based on bit expression. Recently, I find a very smart code and one line is like 'i & -i' where i is a integer. How to understand the result of 'i & -i'. In addition, how python deal with negative integer '-i' for bit manipulation?

推荐答案

"i& -i"-清除所有位"1"，但最后一位有效. 例如:

"i & -i" - this is clear all bits "1", but last significant one. For example:

i = 10(十进制)= 000010 1 0(bin)

i = 10(dec) = 00001010(bin)

i& -i将为000000 1 0(bin)= 2(dec)

i & -i will be 00000010(bin) = 2(dec)

根据数学术语，"i&-i"返回的最大值为2 ^ N，即"i"的分母.

By math terms, "i & -i" returns maximal 2^N, which is divider of "i".

更多示例:

i(dec)   i(bin)     i&-i
 1            1        1
 5          101        1
 8         1000     1000
12         1100     0100

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