WordPress: get post ID for slug

/**
 * Retrieve a post ID for a slug and post type
 */

function get_postid_by_slug( $page_slug = '', $posttype = 'post' ) {

  if ( $page_slug ) {
    $postobject = get_page_by_path( $page_slug, OBJECT, $posttype );
    if ( $postobject ) {
      return $postobject->ID;
    }
  }
  return 0;

}