"(?=hello)" matches "hello"
".*"        matches "hello Ga"
"[^G]"      matches "g"
"[^a]"      matches "s"
".*"        matches nothing

##</code><code>##

( "hello Gags" =~ /^(?=hello)(?!.*Ga/ )&& print ("Matched") || print ("Unmatched")

##</code><code>##

use strict;
( "hello Gags" =~ /^(?=hello)(.*)([^G][^a])(.*)$/ ) ?  matches() : print ("Unmatched");

sub matches {
  no strict 'refs';
  for (1..10) {
    my $tmp = ${$_} or next;
    print "\$$_ = '$tmp'\n";
  }
  return 1;
}

__OUTPUT__
$1 = 'hello Ga'
$2 = 'gs'