如何使用foreach或SPL在每两个项目中添加一个html元素？

Question

How can I interrupt a loop and adding an html element at each two iterations? Can a simple foreach do that or something in SPL?

<?php foreach($items as $index=>$item): ?>
     <li>$item->title</li>
     <?php if($index + 1 = 2):?>
     <div class="divider"></div>
     <?php endif;?> 
<?php endforeach;?>

html result,

<li>title 1</li>
<li>title 2</li>
<div class="divider"></div>
<li>title 3</li>
<li>title 4</li>
<div class="divider"></div>
<li>title 5</li>
<li>title 6</li>
<div class="divider"></div>

EDIT:

<li>title 1</li>
<li>title 2</li>
<li>title 3</li>
<div class="divider"></div>
<li>title 4</li>
<li>title 5</li>
<div class="divider"></div>
<li>title 6</li>

Answer 1

For this result :

<li>title 1</li>
<li>title 2</li>
<div class="divider"></div>
<li>title 3</li>
<li>title 4</li>
<div class="divider"></div>
<li>title 5</li>
<li>title 6</li>
<div class="divider"></div>

Do this with modulus 2 :

<?php 
foreach($items as $index=>$item) {
  if ($îndex % 2 = 0) {
?>
<?php // <!-- ADD HTML HERE !> ?>
<li>$item->title</li>
<?php
  } else {
?>
<li>$item->title</li>
<?php
  }
}
?>

For this result :

<li>title 1</li>
<li>title 2</li>
<li>title 3</li>
<div class="divider"></div>
<li>title 4</li>
<li>title 5</li>
<div class="divider"></div>
<li>title 6</li>

Do this with skipping the first index and modulus 2 :

<?php 
foreach($items as $index=>$item) {
  if ($îndex != 0 && $îndex % 2 = 0) {
?>
<?php // <!-- ADD HTML HERE !> ?>
<li>$item->title</li>
<?php
  } else {
?>
<li>$item->title</li>
<?php
  }
}
?>