string.split（"（？！^）"）解释 [英] string.split("(?!^)") explanation

问题描述

我正在尝试将String的字符拆分为String数组。我找到了解决方案此处。

I'm trying to split the characters of the String to a String array. I found the solution here.

解决方案是完美的，但我不知道如何 .split（（？！^））工作。我熟悉 split（）方法的基础知识。有人可以提供解释吗？

The solution is perfect, however I don't get how .split("(?!^)") worked. I'm familiar with the basics of split() method. Can someone provide an explanation?

推荐答案

（？！^）是正则表达式，由否定前瞻。 ^ 是锚点表示字符串的开头。 （？！^）匹配所有0长度的字符串，后面跟着 ^ ，字符串的开头。换句话说，它匹配字符串开头的除之外的所有0长度字符串。

(?!^) is a regular expression consisting of a negative lookahead. ^ is an anchor used to signify the start of the string. (?!^) matches all 0-length strings that are not followed by ^, the start of the string. In other words, it matches all 0-length strings except that at the start of the string.

例如，在字符串<$中c $ c> abc ，将有3个匹配：一个在 a 和 b 之间，一个在 b 和 c 之间，一个在 c 。拆分这些匹配会产生所需的数组（请注意， split（）的1参数版本会丢弃任何尾随的空字符串，这就是为什么没有包含在结果数组中的原因） 。

For example, in the string abc, there will be 3 matches: one between a and b, one between b and c, and one after the c. Splitting on these matches produces the desired array (note that the 1-argument version of split() discards any trailing empty strings, which is why none are included in the resulting array).

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