Binary Search in PHP

<?php

class BinarySearch {
   // Assumes 'arr' is in sorted order

   // Iterative implementation of Binary Search
   public static function binarySearchIterative($arr, $num) {
       $low = 0;
       $high = count($arr) - 1;

       while($low <= $high) {
           $mid = (int)(($low + $high) / 2);

           if($num < $arr[$mid]) {
               $high = $mid - 1;
           }
           elseif ($num > $arr[$mid]) {
               $low = $mid + 1;
           }
           else {
               return $mid;
           }
       }
       return -1;
   }

   // Recursive implementation of binary search
   public static function binarySearchRecursive($arr, $num) {
       return BinarySearch::binarySearchRecursiveAux($arr, $num, 0, count($arr) - 1);
   }

   public static function binarySearchRecursiveAux($arr, $num, $low, $high) {
       $mid = (int)(($low + $high) / 2);

       if($low > $high) return -1;

       if($num < $arr[$mid]) {
           return BinarySearch::binarySearchRecursiveAux($arr, $num, $low, $mid - 1);
       }
       elseif($num > $arr[$mid]) {
           return BinarySearch::binarySearchRecursiveAux($arr, $num, $mid + 1, $high);
       }
       else return $mid;
   }
}