It's not possible to combine those regexps if those are trully meant to be captures ((...)) and not groupings ((?:...)). Any joining would change the variables in which the data is captured.

Let's assume that you only used the parens for grouping (and that you forgot $ at the end of each regexp), then you'd be starting with the following:

if ($file =~ /^\d{8}(?:_\d+)*\.ilf$/i ||
    $file =~ /^\d{8}(?:\s\d+)*\.sht$/i
) {
   ...
}

The possibilities for joining are still quite limited since there is a mixture of common and not common elements:

      vvvvvvvvv  vvv vvv   vvvv  common
     /^\d{8}(?:_ \d+)*\.ilf$/ix
     /^\d{8}(?:\s\d+)*\.sht$/ix
               ^^       ^^^      not common

The best that can be done, as far as I can tell, is to join the common beginning and the common ending, as seen in the following code snippet:

if ($file =~ /^\d{8}(?:(?:_\d+)*\.ilf|(?:\s\d+)*\.sht)$/i) {
   ...
}

This is definitely less readable.

This should do for you:

if ($file =~ /^\d{8}((_\d+)*\.ilf|(\s\d+)*\.sht)/i) { ... }

You don't need parens around \d.

Update: What ikegami said about captures vs. grouping. I assumed you were only using the parens for grouping.

Collect the similar terms (^\d{8}, \d+\.) , use alternations for dissimilar ones (_, \s, sht, ilf ...

$file =~ m/ ^ \d{8}
            (
              (?: _ | \s )
              (\d)+
            )*
            \.
            (?: ilf | sht )
          /xi ;

Re^2: File name regex

duff

created: 2006-01-20 02:05:19

perlmonks

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prlmnks

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That would work if he can live with the false positives. i.e., you pattern will match files named 12345678_1.sht and 12345678 1.ilf

duff

Re^2: File name regex

Fletch

created: 2006-01-20 09:23:38

perlmonks

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Erm, and now that you've deleted the previous contents we'll never know what was wrong. It's better form to add an update (possibly bracketing the incorrect parts with <strike> tags) stating that somethings wrong. Now the existing reply to your node makes no sense because it has no context.

I believe this will do what you ask, where if the option '_nnn' is present then the extension should be '.ilf', or if it is ' nnn' then the extension should be '.sht'; whilst capturing the entire optional part to $1 and the last digit of that optional part to $2:

    m[ ^ \d{8} ( (?(?=.* \. ilf) _ | \s ) (\d)+ )* \. (?:ilf|sht) ]x

Whether you would call that a 'shortcut' is debatable.

(Warning: more [cpan://Regexp::Assemble] pimping ahead).

Assuming you do not really care about those captures, if I "unroll" the patterns, it looks like you're interested matching against the following patterns:

^\d{8}\.ilf
^\d{8}_\d+\.ilf
^\d{8}\.sht
^\d{8}\s\d+\.sht

Using the assemble script from the above module, or something like

it produces the following pattern:

... which looks roughly like that the other people came up with manually. If you do need the captures, the pattern becomes

in which case you can perform the match and get the captures with something like