如何根据用户的经验为用户分配费率

What syntax I should use to assign rate to user, if there would be 100 of levels. For aim to avoid hundred lines of code?

function showRank($practice) {

    $ranks = array(     "boy",
                        "student",
                        "master");

    $rank = $ranks[0];

    if ( $practice >= 10 and $practice < 20) {$rank = $ranks[1];}
    else if ($practice >= 20 and $practice < 30) {$rank = $ranks[2];}
    else if ($practice >= 30 and $practice < 40) {$rank = $ranks[3];}

    echo $rank;
}

If you have range of 10 then you can do it.like this

  function showRank($practice) {

    $ranks = array(     "boy",
                        "student",
                        "master");

    $rank = $ranks[0];
    foreach ($ranks as $key => $value) {
        $interval = ($key+1)*10;
        if($practice <= $interval)
        {
            $rank = $value;
            break;
        }
    }


    echo $rank;
}
showRank(20);

If your progression is at a constant rate, do it something like this: create $ranks array like you have

$ranks = array("boy", "student", "master", .....);

As indicated above, taking the progression of ranks to be 10 "points" each, then

$rankId = floor($practice/10);
$rank = $ranks[$rankId];