How to make function for call first image, first url, and post title from Next/P

How to make function for call first image, first url, and post title from Next/Previous posts?

These are custom function for call first image and first url in my functions.php but it using in loop at index.php only.

// Get URL of first image in a post
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];

// no image found display default image instead
if(empty($first_img)){
$first_img = "/images/default.jpg";
}
return $first_img;
}

// Get URL of first url in a post
function catch_that_url() {
global $post, $posts;
$first_url= '';
ob_start();
ob_end_clean();
$output = preg_match_all('/<a.+href=[\'"]([^\'"]+)[\'"].* title="Go to Store">/i', $post->post_content, $matches);
$first_url = $matches [1] [0];

// no image found display default image instead
if(empty($first_url)){
$first_url = "/404.php";
}
return $first_url;
}

However, after I using both function in single.php. It display in an single from itself id product only.

How can I make something changes that make it using as loop as index.php in single.php?

Thanks!