Explain the meaning of the code ((N & (n-1)) = = 0)

Idea: Preliminary view it is difficult to analyze the meaning of the expression at a glance, we might like to analyze the example, assuming that n = 5, the binary is represented as 101, then n-1 = 4, the binary is expressed as, 5 & 4 = 101 & 100 = 100 = 4! = 0, let's look at more examples below

5 4 101  - 4 6 5  the 101 4 7 6 111  the 6 8 7  + 0111 0

We will find that to make the expression equal to 0,n-1, we must make the n-1 of n be 1 high, that is to say, satisfy the condition:

1 =0

Let's see if there are those numbers that can meet the requirements:

 10  & 01  = 0 -------2  ^1  100  & 011  = 0 -------2  ^2  1000  & 0111  = 0 -------2  ^3  01111  = 0 -------2  ^4   > ... 

The so-called code ((N & (n-1)) = = 0) means that n satisfies the n-th-square of 2

The problem is usually to examine the ability to analyze and solve problems.

Explain the meaning of the code ((N & (n-1)) = = 0)