#!/usr/bin/perl use strict; use warnings; my @regexes = (qr/^.{0}$/, qr/^.{0,}$/, qr/^.{0,1}$/, qr/^.{,1}$/); for my $re (@regexes) { }
Standard input is empty
'' =~ /(?^:^.{0}$)/: true
'' =~ /(?^:^.{0,}$)/: true
'' =~ /(?^:^.{0,1}$)/: true
'' =~ /(?^:^.{,1}$)/: false