woocommerce_format_postcode │ filter-hook │ WC 1.0

Usage

add_filter( 'woocommerce_format_postcode', 'wp_kama_woocommerce_format_postcode_filter', 10, 2 );

/**
 * Function for `woocommerce_format_postcode` filter-hook.
 * 
 * @param  $trim    
 * @param  $country 
 *
 * @return 
 */
function wp_kama_woocommerce_format_postcode_filter( $trim, $country ){

	// filter...
	return $trim;
}

$trim

-

$country

-

Where the hook is called

return apply_filters( 'woocommerce_format_postcode', trim( $postcode ), $country );

Where the hook is used in WooCommerce