Wordpress - Echo Category-Slugs in Loop

Question

I am trying to echo multiple catgory-slugs instead of the category-names in a Wordpress-Loop in the archive.php

My Code looks like this and I tried a lot so far, but nothing seems to work. All I achieved was to receive the first slug of a category, but not all of them:

    <li class="<?php the_category( ' ' ); ?> ">
        <div class="content">
            <h4><?php the_title(); ?></h4>
        </div>
    </li>

Answer 1

Below code should work

<?php
$categories = get_the_category();
$cls = '';

if ( ! empty( $categories ) ) {
  foreach ( $categories as $cat ) {
    $cls .= $cat->slug . ' ';
  }
}
?>
<li class="<?php echo $cls; ?> ">
    <div class="content">
        <h4><?php the_title(); ?></h4>
    </div>
</li>