$arr = array(1, 4, 6, 1, 8, 9, 4, 6); $unique = array_unique($arr); $duplicates = array_diff_assoc($arr, $unique); print_r($duplicates); Array ( [3] => 1 [6] => 4 [7] => 6 )
$counts = array_count_values($array); $duplicate_title = array_filter($array, function ($value) use ($counts) { return $counts[$value] > 1; });
function has_dupes($array) { $dupe_array = array(); foreach ($array as $val) { if (++$dupe_array[$val] > 1) { return true; } } return false; }