how i can retrieve all woocommerce orders in new custom plugin

i tried to use wc_get_orders() function to retrieve all woocommerce orders but i got

"Uncaught Error: Call to undefined function wc_get_orders()"

and did this

require_once '../woocommerce/includes/wc-order-functions.php'; 

but i got

require_once(../woocommerce/includes/wc-order-functions.php): failed to open stream: 

how i can retrieve all woocommerce orders