这是什么布尔回报是什么意思？ [英] What does this boolean return mean?

问题描述

在codeReview 我贴code的工作一块，要求提示，以改善它。其中我是使用一个布尔方法来检查，如果一个ArrayList有偶数个指标（这是必需的）。这是code的建议：

On CodeReview I posted a working piece of code and asked for tips to improve it. One I got was to use a boolean method to check if an ArrayList had an even number of indices (which was required). This was the code that was suggested:

private static boolean isEven(int number)
{
    return (number & 1) == 0;
}

正如我已经纠缠，对于很多帮助特定的用户，我已经决定它的时间我缠着多所社区！我真的不明白这是如何工作。该方法被调用，并采取ArrayList的大小作为参数（即ArrayList中有十个元素，数= 10）。

As I've already pestered that particular user for a lot of help, I've decided it's time I pestered the SO community! I don't really understand how this works. The method is called and takes the size of the ArrayList as a parameter (i.e. ArrayList has ten elements, number = 10).

我认识一个＆放大器; 运行数量和1的比较，但我得到了后失去

I know a single & runs the comparison of both number and 1, but I got lost after that.

我看了它的方式，跟它返回真，如果若干== 0 和 1 == 0 。我知道，第一是不正确的，而后者显然没有意义。任何人可以帮助我呢？

The way I read it, it is saying return true if number == 0 and 1 == 0. I know the first isn't true and the latter obviously doesn't make sense. Could anybody help me out?

编辑：我也许应该补充一点，code不工作，如果你想知道

推荐答案

请记住，与＆amp;是按位运算。你也许是意识到了这一点，但它根据您所提出的问题的方式并不完全清楚我的。

Keep in mind that "&" is a bitwise operation. You are probably aware of this, but it's not totally clear to me based on the way you posed the question.

话虽这么说，理论的想法是，你有一些int，它可以通过一些系列1和0的位pssed前$ P $。例如：

That being said, the theoretical idea is that you have some int, which can be expressed in bits by some series of 1s and 0s. For example:

...10110110

在二进制的，因为它是基体2，每当数的按位版本在0结束时，它是偶数，并且当它在1结束它为奇数。

In binary, because it is base 2, whenever the bitwise version of the number ends in 0, it is even, and when it ends in 1 it is odd.

因此​​，做一个按位＆安培;用1对上面是：

Therefore, doing a bitwise & with 1 for the above is:

...10110110 & ...00000001

当然，这是0，所以你可以说，原来的输入均匀。

Of course, this is 0, so you can say that the original input was even.

另外，考虑奇数。例如，添加1到我们上面了。然后

Alternatively, consider an odd number. For example, add 1 to what we had above. Then

...10110111 & ...00000001

时等于1，并且因此，不等于零。瞧。

Is equal to 1, and is therefore, not equal to zero. Voila.

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