如何通过移位将多个小整数保存在一个整数中? [英] How do I save multiple small integers in one integer via bitshifting?

问题描述

我在int[][][]数组中工作，我需要从静态函数返回该数组一个字段的地址. 考虑到数组的维数将保持较小(int[32][32][32])的事实，我想到了返回一个包含所有三个值的数字，而不是使用包含三个数字的数组.

I am working in an int[][][] array and I need to return an address of one field of that array from a static function. Given the fact that the dimensions of the Array will stay small (int[32][32][32]) I had the idea to return one number containing all three Values, instead of using an Array containing the three numbers.

我已经有了一个可行的解决方案，我将我的电话号码打包成一个字符串，然后通过Integer.parseInt(String)在接收方法中将其解压缩. 不幸的是，这在运行时方面效果不佳，所以我想到了移位.

I already had a working solution, where i packed my number into a String and unpacked it in the receiving method via Integer.parseInt(String). Unfortunately this didn't work quite, well in terms of runtime, so i thought of bitshifting.

对于我的英语不好，我深表歉意，希望这个简单的问题值得您珍惜:)

I apologize for my bad english and hope this simple question is worth your time :)

推荐答案

如果您的数字在0 ... 255范围内，此示例会将三个数字编码为一个int，然后再次对其进行解码...

If your numbers are in the range 0...255, this example will encode three numbers into one int and then decode it again...

public class BitDemo {

    public static void main(String[] args) {
        int encoded = encode(20, 255, 10);
        int[] decoded = decode(encoded);

        System.out.println(Arrays.toString(decoded));
    }

    private static int[] decode(int encoded) {
        return new int[] {
                encoded & 0xFF,
                (encoded >> 8) & 0xFF,
                (encoded >> 16) & 0xFF
        };
    }

    private static int encode(int b1, int b2, int b3) {
        return (b1 & 0xFF) | ((b2 & 0xFF) << 8) | ((b3 & 0xFF) << 16);
    }
}

(b1 & 0xFF)-获取b1的前8位

((b2 & 0xFF) << 8)-获取b2的前8位并将其左移8位

((b2 & 0xFF) << 8) - Gets the first 8 bits of b2 and shifts them left 8 bits

((b3 & 0xFF) << 16)-获取b3的前8位并将其左移16位

((b3 & 0xFF) << 16) - Gets the first 8 bits of b3 and shifts them left 16 bits

这三个数字相加或.

如果您使用负数或大于255的数字，则会得到不同的结果.

If you have negative numbers or number more than 255, you'll get different results.

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