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 :$array = array(1,2,2,4,5)
function returndup($array) should return 2 ;

if array is array(1,2,1,2,5);
it should return an array with 1,2

Ayrıca, ilk dizi her zaman 5 pozisyonları uzunluğunda