regex match text in either single or double quote

Question

I want to match strings like:

The sentence is 'He said "Hello there"'
The sentence is "He said 'Hello there'"

and get back a single capture (match) that is the sentence inside the outer single or double quotes.

^The sentence is (?:(?:'([^']*)')|(?:"([^"]*)"))$

The above regex gives me back 2 captured groups, one of them empty and the other containing the desired sentence.

^The sentence is (['"])(.*)\1$

Returns the quotation mark (single or double quote) as the 1st group and the sentence as the 2nd group.

If I make the first group non-capturing,

^The sentence is (?:['"])(.*)\1$

then I cannot use the later reference to the captured group. (the \1 is, of course, no longer referring to the single or double quote match)

Is there a way to have groups whose "capture" can be referenced later in the regex, but whose captured value is not returned in the list of matches?

Or some other way to solve my (seemingly simple) problem.

If you also expect escaped quotes inside, see this answer. The technique used is even of nice performance. — bobble bubble
– bobble bubble, Commented Nov 20, 2019 at 9:39

redisko · Accepted Answer · 2018-07-19 23:41:06Z

19

Very sad, but such an elegant and accurate way does not work:

(["'])(?:\\\1|[^\1]+)*\1

But we can change it a little bit, and all works fine:

(["'])((?:\\\1|(?:(?!\1)).)*)(\1)

https://regex101.com/r/dKdBMT/2

I would like to make sure that this regexp will work in all cases: please more test it.

edited Jul 19, 2018 at 23:41

answered Jul 19, 2018 at 22:57

redisko

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Comments

Egan Wolf · Accepted Answer · 2017-10-27 04:35:19Z

16

This one seems to work:

(?:'|").*(?:'|")

or

((?:'|").*(?:'|"))

if you need a group.

Here's the demo: link

It works, because * is a greedy quantifier, so you don't have to know what kind of quote is in the end. * will take as much as possible.

answered Oct 27, 2017 at 4:35

Egan Wolf

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6 Comments

Phil Davis Over a year ago

The first example does not actually capture anything. The second example captures the sentence including the outer single or double quotes. A combination works: (?:'|")(.*)(?:'|")

Egan Wolf Over a year ago

I thought, you want to capture quotation signs as well, didn't go back to question to check it. I'm glad it helped.

Phil Davis Over a year ago

Not knowing whether the first quote is single or double means that unbalanced sentences get matched: The sentence is "abc 123' and 'He said "Goodbye" and the last of those returns He said "Goodbye as the sentence. It would be nice to not match such strings with unbalanced quotes.

Egan Wolf Over a year ago

Check this regex (?:'|")(.*(?:'|").*(?:'|"))(?:'|") and demo. It still can not be perfect as I don't know what kind of cases you have, but it should help you.

tgoneil Over a year ago

No. This will match the regex: 'ss"

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tgoneil · Accepted Answer · 2018-03-06 18:34:55Z

6

You want to make sure the quote symbols are properly matched, so a quote starting with a single quote ends with a single quote. Also, the regex should allow for escaping a quote symbol with a backslash if it's the same symbol (double or single quote symbol) bounding the string. Try this:

"(?:[^"\\]|\\.)*"|'(?:[^'\\]|\\.)*'

These samples match this regex:

'sing"le q\'uote'

"dou\"ble 'quote"

answered Mar 6, 2018 at 18:34

tgoneil

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Comments

Yogesh Sonawane · Accepted Answer · 2020-12-20 05:20:41Z

1

One of above is very accurate. But, needs some updates. Here it is:

(["'])((?:\\1|(?:(?!\1)).)*)(\1)

This will match everything as string literals.

answered Dec 20, 2020 at 5:20

Yogesh Sonawane

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1 Comment

Yogesh Sonawane Over a year ago

Now, I want to match { OR } braces except matching pattern (["'])((?:\\1|(?:(?!\1)).)*)(\1) in same string. I'm trying but no luck..

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