Нужная категория при добавление новостей

<input name="catlist[]" type="checkbox" style="display: none;" value="id категории">

                    if( is_array( $categoryid ) ) {
                        foreach ( $categoryid as $element ) {
                            if( $element == $id ) $returnstring .= 'SELECTED';
                        }
                    } elseif( $categoryid == $id ) $returnstring .= 'SELECTED';

                    if( is_array( $categoryid ) ) {
                        foreach ( $categoryid as $element ) {
                            if( $element == $id ) $returnstring .= 'SELECTED';
                        }
                    } elseif( $categoryid == $id ) { 

                                             $returnstring .= 'SELECTED'; 

                                       } elseif (  АЙДИ_ВАШЕЙ КАТЕГОРИИ == $id     )  {

                                              $returnstring .= 'SELECTED';
                                       }

АЙДИ_ВАШЕЙ КАТЕГОРИИ == $id

in_array ( $id, array ( 1,2,3 ) )