Re: Regex question - identify which pattern comes first

if ( /(BA[ABC]{2})|(CA[CD]{2})|(DA[SC]{2})/ ) {
   my $first =
     ( defined( $1 ) ? 1
     : defined( $2 ) ? 2
     : 3
     );

   ...
}
[download]

local our $first;

/
   (?: BA[ABC]{2} (?{ $first = 1; })
   |   CA[CD]{2}  (?{ $first = 2; })
   |   DA[SC]{2}  (?{ $first = 3; })
/x;
[download]

Update: I had mixed up (??{ }) and (?{ }). Fixed.

Comment on Re: Regex question - identify which pattern comes first Select or Download Code

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Re^2: Regex question - identify which pattern comes first by harangzsolt33 (Deacon) on May 02, 2026 at 02:15 UTC
Oh wow, that is an amazingly simple solution! Thank you so much!!! :-)	[reply]
Re^3: Regex question - identify which pattern comes first by LanX (Saint) on May 02, 2026 at 13:28 UTC
> that is an amazingly simple solution! Did you try it? These `(??{ $first = 1; })` won't work because they'll include 1,2 or 3 into the regex. Try `(?{ $first = 1; })`; with a single `?` instead. Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery} Thus	[reply] [d/l] [select]
Re^4: Regex question - identify which pattern comes first by harangzsolt33 (Deacon) on May 02, 2026 at 14:20 UTC
No, the second solution did not work. But the first one does work, and I never thought of doing it that way even though I knew you could capture using the parentheses. I didn't know you can use defined to figure out which one of the patterns was captured. The second solution, I think, requires a more modern Perl interpreter. I use Perl 5.8 mostly. It said unmatched regex --> / something... But it's okay. I'll use the first solution. I think, it's also easier to read.	[reply]
Re^5: Regex question - identify which pattern comes first by LanX (Saint) on May 02, 2026 at 14:43 UTC