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Extracting String that is contained in Double Quotes, Single Quotes and there can be Quotes within Quotes

jonjon
New User

Nov 12, 2014, 7:46 PM

Post #1 of 5 (40714 views)

Extracting String that is contained in Double Quotes, Single Quotes and there can be Quotes within Quotes	Can't Post

["|'](.*)["|']

The above RegEx script will parse out any number of characters that fall between a single or double quote.

1 example "jon" will be extracted into a list as jon (Double Quotes)
2 example 'don' will be extracted into a list as don (Single Quotes)

But......What if I have something like below

If [Jon is Great] = "01/31/20XX" then "January"

With the Regex above, the output would be the following:

01/31/20XX" then "January

My desired output would be :

01/31/20xx
January

Zhris
Enthusiast

Nov 13, 2014, 10:01 AM

Post #2 of 5 (40696 views)

Re: [jonjon] Extracting String that is contained in Double Quotes, Single Quotes and there can be Quotes within Quotes [In reply to]	Can't Post

Hi,

Regular expression quantifiers are greedy by default i.e. they will match as much as possible. You can force quantifiers to be ungreedy by following them with a question mark i.e. they will match as little as possible:

Code

["|'](.*?)["|']

Chris

(This post was edited by Zhris on Nov 13, 2014, 10:04 AM)

BillKSmith
Veteran

Nov 14, 2014, 1:50 PM

Post #3 of 5 (40611 views)

Re: [jonjon] Extracting String that is contained in Double Quotes, Single Quotes and there can be Quotes within Quotes [In reply to]	Can't Post

Chris correctly identified the problem with your example. However, matching quotes can get even more complicated. Consider the following example:

Code

use strict; 
use warnings; 
my $string = q(The cartoon ended with the caption "That's all folks".); 
my ($match) = $string =~ m/ ["'](.*?)["']/; 
print $match;

OUTPUT:

Code

That

What you want is "That's all folks".

The module Regexp::Common qw(balanced) is by far the best solution.
Good Luck,
Bill

jonjon
New User

Nov 14, 2014, 2:43 PM

Post #4 of 5 (40599 views)

Re: [BillKSmith] Extracting String that is contained in Double Quotes, Single Quotes and there can be Quotes within Quotes [In reply to]	Can't Post

Thank you Zhris and Bill. However, I want the Regex to Pull the date and then I want it to extract January. In both example it will only extract the first term in quotes, which is the 01/31/20xx - I then need the regex to parse out the January seperately as well.

If [Jon is Great] = "01/31/20XX" then "January"

With the Regex above, the output would be the following:

01/31/20XX" then "January

My desired output would be :

01/31/20xx
January

Laurent_R
Veteran / Moderator

Nov 15, 2014, 5:33 AM

Post #5 of 5 (40432 views)

Re: [jonjon] Extracting String that is contained in Double Quotes, Single Quotes and there can be Quotes within Quotes [In reply to]	Can't Post

If you want to capture several items, you can do it in a list context, as in this example under the Perl debugger:

Code

  DB<1>  $_ = 'If [Jon is Great] = "01/31/20XX" then "January" ' 
 
  DB<2>  @matches = /"(.*?)"/g; 
 
  DB<3> x \@matches; 
0  ARRAY(0x600500ae8) 
   0  '01/31/20XX' 
   1  'January' 
  DB<4>

Having said that, I agree with Bill that the module Regexp::Common qw(balanced) is most probably a better solution.

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