WordPress :: How to get get_query_var working

custom_query_var.php

<?php

// register query_var on funtions.php
add_filter('query_vars', 'add_my_var');
function add_my_var($public_query_vars) {
    $public_query_vars[] = 'your_query_var';
    return $public_query_vars;
}

// get query var
$your_query_var = get_query_var('your_query_var', 1);