Check if the post has at least one image and display it

<?php
// ADD THIS IN THE functions.php FILE
 
function catch_that_image() {
  global $post, $posts;
  $first_img = '';
  ob_start();
  ob_end_clean();
  $output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches);
  $first_img = $matches [1] [0];
 
  if(empty($first_img)){ //Defines a default image
    $first_img = "/uploads/default.jpg";
  }
  return $first_img;
}?>
 
---------------------------------------------------------------------
 
<?php
 
// ADD THIS IN THE DESIRED TEMPLATE FILE
 
	$content = $post->post_content;
	$searchimages = '~<img [^>]* />~';
 
	/*Run preg_match_all to grab all the images and save the results in $pics*/
 
	preg_match_all( $searchimages, $content, $pics );
 
	// Check to see if we have at least 1 image
	$iNumberOfPics = count($pics[0]);
 
	if ( $iNumberOfPics > 0 ) { ?>
        <!-- GRAB THE IMAGE AND USE WHATEVER HTML YOU LIKE -->
          <img src="<?php echo catch_that_image() ?>" alt="<?php the_title(); ?>" /></a>
	<?php }
 
?>