Regex: question about ?= and any characters

Question

I have a target string like:

   "addr: line1 
         line2

      tel:12345678"

note: between line2 and tel, there might be 1 or multiple new lines:\r\n or \r\n\r\n or more. The result I want to get is as below:

   "addr: line1 
         line2"

no \r\n under line2.

My questions are:

1)If I use

/addr[\s\S]+(?=(\r\n)+tel)/

, i will get the addr without tel, but I can't get rid of "\r\n"s under "line2", how could I do that?

2)I know [\s\S] represents any characters including \r,\n, and (.|\n|\r) can do that too. But why [.\n] can't? It's just like the syntax of[\s\S] isn't it?

Thank you very much!

Why not just use TrimEnd to get rid of the trailing whitespace? — Klaus Gütter, Sep 21 '19 at 05:45
Thank you! That's what I am currently doing, but I am curious if there is another way. — a_pp, Sep 21 '19 at 06:00

score 0 · Accepted Answer · answered Sep 21 '19 at 06:07

0

You need to make the first "+" non-greedy, so that it does not match the whole whitespace before "tel"

  var regex = new Regex(@"addr.+?(?=\s+tel)", RegexOptions.Singleline);
  var result = regex.Match(text).Value;

answered Sep 21 '19 at 06:07

Klaus Gütter

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Added a demo on [regex101.com](https://regex101.com/r/U35eq7/1), +1. – Jan Sep 21 '19 at 06:13
Thank you Klaus! now I understand adding a ? can make + non-greedy, that works perfectly! (although I needed to alter your pattern to "addr[\s\S]+?(?=(\r\n)+tel)" to adapt my string strictly). BTW, do you have any idea about my 2nd question? – a_pp Sep 21 '19 at 06:25

Regex: question about ?= and any characters

1 Answers1