How to add a slash for all items except the last one?

Question

PHP

I'm not strong in PHP, so I'm asking how to add
slashes for the emerging list? The list turns out like this to make that for the last did not form?

<?if (!empty($categories)): ?>
<div style="margin: 100px 0 33px -40px;">
  <ul class="categories1">
  <?foreach ($categories as $catId => $cat):?>
    <li><a href="<? echo $cat['LINK']?>"><? echo $cat['NAME']; ?></a></li>
  <?endforeach;?>
  </ul>
</div>
<?endif;?>

Answer 1

maybe easier to style?

ul>li {
    display: inline-block
}
ul>li+li:before {
    padding: 0 5px;
    color: #ccc;
    content: "/\00a0"
}