show featured image in post wordpress

1if ( has_post_thumbnail()) {
2   $large_image_url = wp_get_attachment_image_src( get_post_thumbnail_id(), 'large');
3   echo '<a href="' . $large_image_url[0] . '">';
4   the_post_thumbnail('thumbnail');
5   echo '</a>';
6}
7

1<?php if (has_post_thumbnail( $post->ID ) ): ?>
2  <?php $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'single-post-thumbnail' ); ?>
3  <div id="custom-bg" style="background-image: url('<?php echo $image[0]; ?>')">
4
5  </div>
6<?php endif; ?>

1<?php 
2/* RETURNS a full image resource as: <img class="data..." src="data...">
3   ALL parameters are optional. Not needed if you are on WP LOOP
4*/
5echo get_the_post_thumbnail( $the_query->ID, array( 500, 400) ); 
6/* USE get_the_post_thumbnail_url() to get only the image url */
7?>

1<?php echo the_post_thumbnail(); ?>

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