Hi

Regexp::English

#!/usr/bin/perl --
use Regexp::English;
print Regexp::English ->new
    ->remember
    ->multiple
    ->digit, "\n";
__END__
(?^:((?:\d+)))
[download]

Becomes

my( @numbers ) = $str -~  m{ (\d+) }gx;
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/g means global match (match them all), x means ignore literal white space in pattern

YAPE::Regex::Explain can explain a lot of these (though it could use some updating)

use YAPE::Regex::Explain;
print YAPE::Regex::Explain->new(
qr{ (\d+) }x,
)->explain;
__END__
The regular expression:

(?x-ims: (\d+) )

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?x-ims:                 group, but do not capture (disregarding
                         whitespace and comments) (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n):
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
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See also Visual (perl/Tk) regex tweaking utility (its like a living cheatsheet). See also perlrequick

And see Regexp::Common

$ perl -MRegexp::Common -e " print $RE{num}{int} "
(?:(?:[+-]?)(?:[0123456789]+))
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And the magic of /x revealed

#!/usr/bin/perl --
use strict; use warnings;
my $REint = qr{
#---------------------------------------------------------------------
+-
  (?:                  #    group, but do not capture:
#---------------------------------------------------------------------
+-
    (?:                #      group, but do not capture:
#---------------------------------------------------------------------
+-
      [+-]?            #        any character of: '+', '-' (optional
                       #        (matching the most amount possible))
#---------------------------------------------------------------------
+-
    )                  #      end of grouping
#---------------------------------------------------------------------
+-
    (?:                #      group, but do not capture:
#---------------------------------------------------------------------
+-
      [0123456789]+    #        any character of: '0', '1', '2', '3',
                       #        '4', '5', '6', '7', '8', '9' (1 or
                       #        more times (matching the most amount
                       #        possible))
#---------------------------------------------------------------------
+-
    )                  #      end of grouping
#---------------------------------------------------------------------
+-
  )                    #    end of grouping
#---------------------------------------------------------------------
+-
}x; # end of qr

print "$_\n" for "1 plus 1 is 2" =~ m/$REint/g
__END__
1
1
2
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