Check and return duplicates array php

Question

I would like to check if my array has any duplicates and return the duplicated values in an array. I want this to be as efficient as possible.

Example:

$array = array( 1, 2, 2, 4, 5 ); function return_dup($array); // should return 2  $array2 = array( 1, 2, 1, 2, 5 ); function return_dup($array2); // should return an array with 1,2 

Also the initial array is always 5 positions long

Answer 1

this will be ~100 times faster than array_diff

$dups = array(); foreach(array_count_values($arr) as $val => $c)     if($c > 1) $dups[] = $val; 

Answer 2

You can get the difference of the original array and a copy without duplicates using array_unique and array_diff_assoc:

array_diff_assoc($arr, array_unique($arr))