php - Wordpress "get_post_class" get category as string -

as title states, want output class of category onto looped queries.

at moments use post class want add 1 class , have set number of classes. me getting 1 or more values array , echo'ing them out string loop template.

array(7) {     [0]=> string(8) "post-170"     [1]=> string(4) "post"     [2]=> string(9) "type-post"     [3]=> string(14) "status-publish"     [4]=> string(15) "format-standard"     [5]=> string(6) "hentry"     [6]=> string(22) "category-uncategorised" } 

currently

<?php $counter = 0;  $query = new wp_query(array(     'post_type'      => 'post',     'posts_per_page' => '50' ));  if ( $query->have_posts() ) : while ( $query->have_posts() ) : $query->the_post(); ?>      // update counter     $counter++;      <div class="newsfeed__blk <?php echo 'is--' . $counter; ?> col-md-4 col-sm-6 col-xs-12 <?php get_post_class([6]); ?>">...</div>  <?php endwhile; endif; wp_reset_query(); ?> 

end result

i want newsfeed testimonials. in wordpress assign category post. when page rendered query add custom class differentiate dom element custom scss styles.