added get_by_array

tools.php

@@ -183,4 +183,23 @@
     {
         echo get_button_link($text,$style,$link);
     }
+
+    function get_by_array($array,$key)
+    {
+        if(in_array($key,$array))
+        {
+            echo 'find '.$key.' in array';
+            return $array[$key];
+        }
+        else
+        {
+            echo "can't find ".$key.' in array ';
+            return null;
+        }
+    }
+
+    function get_by_get($key)
+    {
+        return get_by_array($_GET,$key);
+    }
 ?>