// Array revert

$arr2 = [2 , 5, 7, 9];

$arr2size = count($arr2)-1;
$i=2;

for ($i=0; $i <=$arr2size; $i++){
    $temp = $arr2[$i];
         for ($j=2; $j <=0; $j--){
            $temp=$arr2[$j];
    }
        }

echo($temp);