Online PHP editor | output for 7o56f

<?php function find_group($cond, &$arr, $e = null) { if (! empty($arr) && ($e === null || $cond($e, reset($arr)))) { $ne = array_shift($arr); return array_merge([$ne], find_group($cond, $arr, ($e === null) ? $ne : $e)); } return []; } function array_group($cond, $arr) { if (empty($arr)) return []; return array_merge([find_group($cond, $arr)], array_group($cond, $arr)); } function it($m,$p){echo ($p?'OK':'NO')." It $m\n";} function eq($a,$b) {return $a==$b;} echo it ('groups', array_group('eq', [1,5,5,6,6,6,7,9]) == [[1],[5,5],[6,6,6],[7],[9]]); echo it ('groups by comparing with first item of each group', array_group(function ($a, $b) { return ($a == ($b-1)) || ($a==$b); }, [1,1,2,3,1]) == [[1,1,2],[3],[1]]); echo it ('groups by comparing with first item of each group', array_group(function ($a, $b) { return ($a == ($b-1)) || ($a==$b); }, [1,1,2,1,3,1]) == [[1,1,2,1],[3],[1]]);