Adding div class based on PHP variable from ACF repeater field?

Question

I am looping through a repeater field in Advanced Custom Fields and displaying divs for each item in the repeater. If the index is equal to 0 , I want to add a special class to just that div. Is this possible? Here's what I've tried:

<?php if (have_rows('products')): $i = 0; ?>
<div class="product-container">
    <?php while (have_rows('products')) : the_row(); ?>
    <div class="product <?php if ($i == 0) { echo 'active-class'; } ?>"></div>
    <?php $i++; endwhile; ?>
</div>
<?php endif; ?>

Unfortunately this is not working.

Answer 1

Instead of doing the conditional within the class, I just did it on the outside and defined two different class tags based on the condition:

<?php if (have_rows('products')): $i = 0; ?>
<div class="product-container">
    <?php while (have_rows('products')) : the_row(); ?>
    <div <?php if ($i == 0) { ?>class="product active"<?php } else { ?>class="product"<?php } ?> ></div>
    <?php $i++; endwhile; ?>
</div>
<?php endif; ?>