III数组处理问题

Question

<?php
$like=array("滑板","溜冰","羽毛球","篮球","足球","登山","台球","文学","IT","美术","旅游","黑客","电子竞技","网游","音乐","极限运动");
$i=1;
foreach($like as $index=>$value){
    if (in_array($index,array('1','2','4','6','9','13','14','16'))){
        echo "<input type=checkbox name=\"userEnrol[]\" value=$index checked>$value";
    }else{
        echo "<input type=checkbox name=\"userEnrol[]\" value=$index >$value";
    }
    if (($i % 4)==0){
        echo "<br>";
    }    
    $i++;
}
?>