#!/usr/bin/perl
use strict;

my $string = "Testing \tthis regex";

print $string, "\n";

$string =~ /(?<=\t)\w+/;
my $string1 = $&;

$string =~ /\t\w+/;
my $string2 = $&;

print "/(?<=\\t)\w+/:\n" . $string1 . "\n";
print "/\\t\w+/:\n" . $string2 . "\n";