Added new Binary Search algorithm in PHP (#426)

Author: arturobp3

Searching/Binary Search/PHP/BinarySearch.php

@@ -0,0 +1,26 @@
+<?php
+
+    function binarySearch($list, $item){
+        $leftIndex = 0;
+        $rightIndex = sizeof($list);
+        
+        while($leftIndex <= $rightIndex){
+            $middleIndex = intdiv(($leftIndex + $rightIndex), 2);
+            
+            if($list[$middleIndex] < $item){
+                $leftIndex = $middleIndex + 1;
+            }
+            else if ($list[$middleIndex] > $item){
+                $rightIndex = $middleIndex - 1;
+            }
+            else{
+                return $middleIndex;
+            }
+        }
+        return -1;
+    }
+    
+    // Simple demonstration of the function
+    $array = array(1, 2, 4, 5, 6, 8, 9, 10, 14);
+    echo binarySearch($array, 8);
+?>