Call current class for wordpress menu tab

Step 1: goto wp-includes/nav-menu-template.php
 
Paste this code near about line 87 and see magic

        $test=esc_attr( $item->url);
       
        $cuurrent_url ="http://".$_SERVER["HTTP_HOST"] . $_SERVER["REQUEST_URI"];
       
       
       
        if($test==$cuurrent_url)
        {
        $attributes .= "class='current'";
       
        }
        if($test=="index.php" && empty($_GET['page_id']))
        {
            $attributes .= "class='current'";
       
        }