Get the keys for duplicate values in an array

Question

I have the following array:

$myarray = Array(\"2011-06-21\", \"2011-06-22\", \"2011-06-22\", \"2011-06-23\", \"2011-06-23\", \"2011-06-24\", \"2011-06-24\",         


        

Answer 1

function getDuplicateValueKeys($my_arr, $clean = false) 
{
    if ($clean) {
        return array_unique($my_arr);
    }
    $dups = array();
    $new_arr = array();
    $dup_vals = array();

    foreach ($my_arr as $key => $value) {
        if (!isset($new_arr[$value])) {
            $new_arr[$value] = $key;
        } else {
            array_push($dup_vals,$value);
        }
    }

    foreach ($my_arr as $key => $value) {
        if (in_array($value, $dup_vals)) {
            if (!isset($dups[$value])) {
                $dups[$value]=array($key);
            }else{
                array_push($dups[$value],$key);
            }
        }
    }

    return $dups;
}