note 99073 added to function.array-filter

A function that allows filtering an array by keys: <?php function array_filter_key( $input, $callback ) { if ( !is_array( $input ) ) { trigger_error( 'array_filter_key() expects parameter 1 to be array, ' . gettype( $input ) . ' given', E_USER_WARNING ); return null; } if ( empty( $input ) ) { return $input; } $filteredKeys = array_filter( array_keys( $input ), $callback ); if ( empty( $filteredKeys ) ) { return array(); } $input = array_intersect_key( array_flip( $filteredKeys ), $input ); return $input; } ?> Example: <?php $input = array_flip( range( 'a', 'z' ) ); $consonants = array_filter_key( $arr, function( $elem ) { $vowels = "aeiou"; return strpos( $vowels, strtolower( $elem ) ) === false; } ); ?> Outputs: array(21) { ["b"]=> int(1) ["c"]=> int(2) ["d"]=> int(3) ["f"]=> int(5) ["g"]=> int(6) ["h"]=> int(7) ["j"]=> int(9) ["k"]=> int(10) ["l"]=> int(11) ["m"]=> int(12) ["n"]=> int(13) ["p"]=> int(15) ["q"]=> int(16) ["r"]=> int(17) ["s"]=> int(18) ["t"]=> int(19) ["v"]=> int(21) ["w"]=> int(22) ["x"]=> int(23) ["y"]=> int(24) ["z"]=> int(25) } ---- Server IP: 69.147.83.197 Probable Submitter: 193.105.64.1 ---- Manual Page -- http://www.php.net/manual/en/function.array-filter.php Edit -- https://master.php.net/note/edit/99073 Del: integrated -- https://master.php.net/note/delete/99073/integrated Del: useless -- https://master.php.net/note/delete/99073/useless Del: bad code -- https://master.php.net/note/delete/99073/bad+code Del: spam -- https://master.php.net/note/delete/99073/spam Del: non-english -- https://master.php.net/note/delete/99073/non-english Del: in docs -- https://master.php.net/note/delete/99073/in+docs Del: other reasons-- https://master.php.net/note/delete/99073 Reject -- https://master.php.net/note/reject/99073 Search -- https://master.php.net/manage/user-notes.php