不包含特定字符串的正则表达式 [英] Regular expression that doesn't contain certain string

问题描述

我有这样的东西

aabbabcaabda

aabbabcaabda

为了选择由 a 包裹的最小组，我有这个 /a([^a]*)a/ 效果很好

for selecting minimal group wrapped by a I have this /a([^a]*)a/ which works just fine

但是我对 aa 包裹的组有问题，我需要类似的东西/aa([^aa]*)aa/ 这不起作用，我不能像 /aa([^a]*)aa/那样使用第一个code>，因为它会在第一次出现 a 时结束，这是我不想要的.

But i have problem with groups wrapped by aa, where I'd need something like /aa([^aa]*)aa/ which doesn't work, and I can't use the first one like /aa([^a]*)aa/, because it would end on first occurence of a, which I don't want.

一般来说，有没有什么办法，用同样的方式说not contains string我可以用 [^a] 说 not contains character 吗?

Generally, is there any way, how to say not contains string in the same way that I can say not contains character with [^a]?

简单地说，我需要 aa 后跟除序列 aa 之外的任何字符，然后以 aa

Simply said, I need aa followed by any character except sequence aa and then ends with aa

推荐答案

一般来说，编写一个不包含特定字符串的正则表达式是一件很痛苦的事情.对于计算模型，我们必须这样做——你使用一个很容易定义的 NFA，然后将其简化为正则表达式.不包含cat"的事物的表达大约有 80 个字符长.

In general it's a pain to write a regular expression not containing a particular string. We had to do this for models of computation - you take an NFA, which is easy enough to define, and then reduce it to a regular expression. The expression for things not containing "cat" was about 80 characters long.

我刚刚完成，是的，它是:

I just finished and yes, it's:

aa([^a] | a[^a])aa

这里是一个非常简短的教程.我之前发现了一些很棒的，但现在看不到了.

Here is a very brief tutorial. I found some great ones before, but I can't see them anymore.

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