Regex Replace everything except between the first " and the last "

Question

i need a regex that replaces everything except the content between the first " and the last ".

I need it like this:

Input String:["Key:"Value""]

And after the regex i only need this:

Output String:Key:"Value"

Thanks!

in your question you say "bracket", in the title you say "double quotes", and in the example your replacing both the brackets and the double quotes. Which is it? — doom87er, Oct 23 '18 at 21:41
Possible duplicate of [Learning Regular Expressions](https://stackoverflow.com/questions/4736/learning-regular-expressions) — Biffen, Oct 24 '18 at 06:43

score 1 · Answer 1 · answered Oct 23 '18 at 23:40

1

You can try something like this.

patern:
^.*?"(.*)".*$

Substion:
$1

On Regex101

Explination:

the first part ^.*?" matches as few characters as possible that are between the start of the string and a double quote

the second part(.*)" makes the largest match it can that ends in a double quote, and stuffs it all in a capture group

the last part .*$ grabs what ever is left and includes it in the match

Finally you replace the entire match with the contents of the first capture group

answered Oct 23 '18 at 23:40

doom87er

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2
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Very good regexp! The `.` does not match newlines, but the original question didn't specify whether that's relevant. If it is, you can use `[^]` instead to match any character. Dart's replace does not have `"$1"` as a replacement pattern. You can do `input.replaceFirstMapped(re, (m) => m[1])` to replace with the first group. – lrn Oct 24 '18 at 06:25
i'm un-familiar with dart. but, if it has Regex options like most other Regex engines then you can use 's' (single-line) to allow `.` to match new-lines – doom87er Oct 24 '18 at 13:06
Sadly (depending on perspective) Dart uses JavaScript's regular expressions. Even in multi-line mode, `.` still doesn't match line terminators. – lrn Oct 24 '18 at 13:14
`[^]` is not a regex to match nothing. It's the beginning of a character class that won't match a right bracket, but it's a syntax error (incomplete character class)... you still need another right bracket, as in `[^]]`. A regex to match nothing would be something like `(?!)`. – Randal Schwartz Oct 24 '18 at 16:20
@RandalSchwartz the goal isn't to match nothing, it's to match any character including new-line. `[^...]` is a negated character class, it matches anything not present in the set. leaving the set empty allows it to match any character. I don't know what you mean by "match nothing" but a negative look ahead without a pattern would prevent your regex from matching anything – doom87er Oct 24 '18 at 16:34
OK, to match any character including newlines, I frequently use `[\d\D]`. – Randal Schwartz Oct 24 '18 at 16:37

lrn · Answer 2 · 2018-10-24T06:31:56.593

Can you say why you need a RegExp? A function like:

String unquote(String input) {
  int start = input.indexOf('"');
  if (start < 0) return input; // or throw.
  int end = input.lastIndexOf('"');
  if (start == end) return input; // or throw
  return input.substring(start + 1, end);
}

is going to be faster and easier to understand than a RegExp.

Anyway, for the challenge, let's say we do want a RegExp that replaces the part up to the first " and from the last " with nothing. That's two replaces, so you can do an

input.replaceAll(RegExp(r'^[^"]*"|"[^"]*$'), "")`

or you can use a capturing group and a computed replacement like:

input.replaceFirstMapped(RegExp(r'^[^"]*"([^]*)"[^"]*$'), (m) => m[1])

Alternatively, you can use the capturing group to select the text between the two and extract it in code, instead of doing string replacement:

String unquote(String input) {
  var re = RegExp(r'^[^"]*"([^]*)"[^"]$');
  var match = re.firstMatch(input);  
  if (match == null) return input; // or throw.
  return match[1];
}

Regex Replace everything except between the first " and the last "

2 Answers2