Binary search PHP implementation

/**Binary search: Find the position of a value in the array
* @$arr: The array of operations, provided that it is arranged in order
* @$val: The value to be searched for
* @$low: The starting position of the search, the default is from the array Find the first number
* @hight: The end position of the search
**/
function binarySearch($arr, $val, $hight, $low=0){
 while($low <= $hight){
 $ mid = ceil($low + ($hight - $low) / 2);
 if($arr[$mid] == $val){
 return $mid;
 }elseif($arr[$mid] > $val){
 $hight = $mid -1;
 }else{
 $low = $mid +1;
 }
 }
 return -1;
}
header('Content-Type: text/html; charset =utf-8');

//Generate an array
$arr = range(0,20);
echo '';</li>
<li>print_r($arr);</li>
<li>echo '' ;

$low = 0;
$hight = count($arr) - 1;
$findVal = rand(0, 20);
$index = binarySearch($arr, $findVal, $hight, $low);
printf("The value '%d' found is the subscript '%s' in the array", $findVal, $index);
?>

PHP