/^([\d.-]*\d[\d.-]*)$/ looks so innocent. It is however a very inefficient regex. Because you give Perl lots of ways of matching the lone \d, it can take a relatively long time for Perl to determine there is a failure. Dropping the \d from the first character class make a huge difference:
#!/usr/bin/perl use strict; use warnings; use Benchmark qw /cmpthese/; our $re1 = qr /^[\d.-]*\d[\d.-]*$/; our $re2 = qr /^[.-]*\d[\d.-]*$/; our @strs = <DATA>; our (@d, @a); foreach (@strs) { die if /$re1/ xor /$re2/ } cmpthese -1 => { davido => 'my @a = map {/$re1/} @strs', abigail => 'my @a = map {/$re2/} @strs', } __DATA__ --1--2--3--4--5--6--7--8--9--0--1--2--3--4--5--6--7--8--9--0--a--2--3- +-4--5-- Rate davido abigail davido 23578/s -- -88% abigail 196495/s 733% --

Abigail


In reply to Re: Golf this reg ex by Abigail-II
in thread Golf this reg ex by bradcathey

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