C＃。逻辑谜题与位操作。只有一个位被设置？ [英] C#. Logical riddle with bit operations. Only one bit is set?

问题描述

这应该是很容易的C ++的人虽然。但有人问我如何做到这一点在C＃。不应该有太大的差异。

的如何找出是否一个长变量的仅一个位置？的

我想不出任何东西，除了一些野蛮的力量转移所有位计数什么集。

解决方案

  

一个非负二进制整数值x，如果 A 2的幂（X及（X-1））使用2的补数算术0

。

2的方幂意味着单个位被置

<一个href=\"http://aggregate.org/MAGIC/#Is%20Power%20of%202\">http://aggregate.org/MAGIC/#Is%20Power%20of%202

编辑：

要允许零案件：

 布尔singleBit = X＆GT; 0安培;＆安培; （X及（X-1））== 0
 

This should be easy for C++ people though. But I was asked how to do it in C#. Shouldnt be much of difference.

How to find out if a long variable has only one bit set?

I cant think anything except some brutal force shifting all bits and counting whats set.

解决方案

A non-negative binary integer value x is a power of 2 if (x&(x-1)) is 0 using 2's complement arithmetic.

Powers of 2 would mean a single bit is set.

http://aggregate.org/MAGIC/#Is%20Power%20of%202

EDIT:

To allow for the zero case:

bool singleBit = x>0 && (x&(x-1))==0

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