private function getInteger($str, $i, $minlength, $maxlength)
{
//match for digits backwards
for ($x = $maxlength; $x >= $minlength; $x--) {
$token = $this->substring($str, $i, $x);
if ($this->length($token) < $minlength) {
return null;
}
if (preg_match('/^\\d+$/', $token)) {
return $token;
}
}
return null;
}