default-qty-zero.php

<?php

/**
 * If you want to set Zero for default quantity value,
 * this function and hook will help you.
 * 
 * @author Saiful Islam <codersaiful@gmail.com>
 */
add_filter('woocommerce_quantity_input_min','wpt_custom_default_quantity_zero');
function wpt_custom_default_quantity_zero(){
	return 0;
}