$ perl -E '
use YAPE::Regex::Explain;
my $e = YAPE::Regex::Explain->new(q{^-?\d+$})->explain;
say $e;
'
The regular expression:
(?-imsx:^-?\d+$)
matches as follows:
NODE EXPLANATION
----------------------------------------------------------------------
(?-imsx: group, but do not capture (case-sensitive)
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
----------------------------------------------------------------------
^ the beginning of the string
----------------------------------------------------------------------
-? '-' (optional (matching the most amount
possible))
----------------------------------------------------------------------
\d+ digits (0-9) (1 or more times (matching
the most amount possible))
----------------------------------------------------------------------
$ before an optional \n, and the end of the
string
----------------------------------------------------------------------
) end of grouping
----------------------------------------------------------------------
I'd also recommend the following documentation:
-
perlrequick - Perl regular expressions quick start
-
perlretut - Perl regular expressions tutorial
-
perlre - Perl regular expressions
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