理解代码({0..1} {0..1} {0..1} {0..1} {0..1} {0..1} {0..1} {0..1 }) [英] Understanding code ({0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1})

问题描述

我在 Bash shell十进制到二进制转换中看到了以下代码我想知道它是如何工作的?我尝试谷歌搜索无济于事.

I saw the following code in Bash shell Decimal to Binary conversion and I was wondering how it works? I tried googling with no avail.

D2B=({0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1})

echo ${D2B[7]}

上面的代码有什么作用?

What does the code above do?

推荐答案

{N..M}，对于整数文字N和M，生成从N到M的整数序列，包括整数(包括空格).这称为"括号扩展"，并且是

{N..M}, for integer literals N and M, generates the series of integers from N to M, inclusively, separated by spaces. This is called a "brace expansion", and is a bashism. As you can see, all brace expansions are done before adding spaces between them.

variable=({some expansion})将每个展开的项目放在数组和${variable[index number]}提取该索引处的值.因此，您的代码有效地以二进制字符串形式返回了数字7.

variable=({some expansion}) puts each of the expanded items in an array, and ${variable[index number]} extracts the value at that index. So your code effectively returns the number seven in binary string form.

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