php如何将ASCII码转成数值

function ascii_to_number($string)
{
  $length = strlen($string);
  $x = 0;
  for ($i = 0; $i < $length; $i++) {
      $x = ($x * 128) + ord($string{$i});
  }
  return $x;
}

$string = "Hello World!";
$number = ascii_to_number($string);
echo "The ASCII number of '{$string}' is: {$number}";