wordpress check for a featured image code example

Example 1: get featured image url in wordpress

if ( has_post_thumbnail()) {
   $large_image_url = wp_get_attachment_image_src( get_post_thumbnail_id(), 'large');
   echo '<a href="' . $large_image_url[0] . '">';
   the_post_thumbnail('thumbnail');
   echo '</a>';
}

Example 2: show featured image in post wordpress

<?php if(has_post_thumbnail()){
  the_post_thumnbail('cstm_name', array( 'class' => 'class1 class2' ))
} else { ?>
  <img class="card-img-top" src="http://placehold.it/750x300" alt="Card image cap" class="img-responsive">
<?php } ?>