将变量匹配到循环中的每个第4个数字 - PHP

Question

I am needing to add a different class at the end of every 4th item that I am looping through. I have done so by:

$i=0;
foreach($mount as $m){
    $i++;
    $startClass = '';
    if($i==4||$i==8||$i==12){$startClass='<div with class>';} //adds class on 4th intervals
    $ret.=''.$startClass.'<other HTML here and such>'; //shorted for readability
}

Now I'm sure there is a more appropriate way to handle this given the fact that if my loop contains 40 objects, I'll need to adjust the if statement accordingly.

I'm recalling an arithmetic formula that might work [an = a1+(n-1)d] but I'm finding that my idea seems off. I apply it (replacing an with i) and it will always = to the equation, thus each item gets the class.

Any suggestions? Thanks in advance!

Answer 1

Use the modulus operator http://www.php.net/manual/en/language.operators.arithmetic.php

if(($i % 4) === 0){
  //add class
}