function binarySearch($low=0, $high, $search)
{
    $mid = ceil(($low+$high) / 2);
    if($search < $mid)
    {
        binarySearch($low, $mid-1, $search);
    } else if($search > $mid)
    {
        binarySearch($mid+1, $high, $search);
    } else
    {
        echo $mid;
    }
}

echo binarySearch(0, 200, 122);