note 104398 added to function.usort

Pretty much the same thing as my previous note, just a little cleaner to use, since the usort call is now folded into the custom 'usortByArrayKey' function. <?php function usortByArrayKey(&$array, $key, $asc=SORT_ASC) { $sort_flags = array(SORT_ASC, SORT_DESC); if(!in_array($asc, $sort_flags)) throw new InvalidArgumentException('sort flag only accepts SORT_ASC or SORT_DESC'); $cmp = function(array $a, array $b) use ($key, $asc, $sort_flags) { if(!is_array($key)) { //just one key and sort direction if(!isset($a[$key]) || !isset($b[$key])) { throw new Exception('attempting to sort on non-existent keys'); } if($a[$key] == $b[$key]) return 0; return ($asc==SORT_ASC xor $a[$key] < $b[$key]) ? 1 : -1; } else { //using multiple keys for sort and sub-sort foreach($key as $sub_key => $sub_asc) { //array can come as 'sort_key'=>SORT_ASC|SORT_DESC or just 'sort_key', so need to detect which if(!in_array($sub_asc, $sort_flags)) { $sub_key = $sub_asc; $sub_asc = $asc; } //just like above, except 'continue' in place of return 0 if(!isset($a[$sub_key]) || !isset($b[$sub_key])) { throw new Exception('attempting to sort on non-existent keys'); } if($a[$sub_key] == $b[$sub_key]) continue; return ($sub_asc==SORT_ASC xor $a[$sub_key] < $b[$sub_key]) ? 1 : -1; } return 0; } }; usort($array, $cmp); }; ?> Examples: 1) Sort a multi-dimensional array by a single key, from least to greatest: usortByArrayKey($resultset, 'order_id'); 2) Sort a multi-dimensional array by a single key, from greatest to least: usortByArrayKey($resultset, 'purchase_amount', SORT_DESC); 3) Sort a multi-dimensional array first by one key, but then by a different key when the first one is equal, both from least to greatest: usortByArrayKey($resultset, array('product_id', 'price')); 4) Sort a multi-dimensional array by two different keys from least to greatest, and then a third from greatest to least if the first two keys map to the equal values: usortByArrayKey($resultset, array('product_id', 'customer_id', 'date'=>SORT_DESC)); 5) Sort a multi-dimensional array by multiple keys, all from greatest to least: usortByArrayKey($resultset, array('product_id', 'price'), SORT_DESC); ---- Server IP: 69.147.83.197 Probable Submitter: 12.169.97.130 ---- Manual Page -- http://www.php.net/manual/en/function.usort.php Edit -- https://master.php.net/note/edit/104398 Del: integrated -- https://master.php.net/note/delete/104398/integrated Del: useless -- https://master.php.net/note/delete/104398/useless Del: bad code -- https://master.php.net/note/delete/104398/bad+code Del: spam -- https://master.php.net/note/delete/104398/spam Del: non-english -- https://master.php.net/note/delete/104398/non-english Del: in docs -- https://master.php.net/note/delete/104398/in+docs Del: other reasons-- https://master.php.net/note/delete/104398 Reject -- https://master.php.net/note/reject/104398 Search -- https://master.php.net/manage/user-notes.php