Custom Field Image to Featured Image In Wordpress

Are you using theme of wordpress which having a proper and professional web design according to your business? Do you have a theme that uses custom fields to hold image URLS and wish you could automatically set these as the featured post image, to be more attuned with other themes if you ever decided to change? Then friends you are lucky due to the code present at "free-php.net". So, here below is the code for you:

Note: "$" is used to declare variable
"preg_match" returns the number of times pattern matches. That will be either no match which is 0 or 1 time.

// First lets get the custom field , we are assuming its called "thumb"
$thumb = get_post_meta($post->ID, 'thumb', true);

// Check if a post thumbnail is already set, if so don't do anything.
if( has_post_thumbnail( $post->ID ) ) {

} else {

if ( ! empty($thumb) ) {

// Download file to temp location
$tmp = download_url( $thumb );

// Set variables for storage
// fix file filename for query strings
preg_match('/[^\?]+\.(jpg|JPG|jpe|JPE|jpeg|JPEG|gif|GIF|png|PNG)/', $thumb, $matches);
$file_array['name'] = basename($matches[0]);
$file_array['tmp_name'] = $tmp;

// If error storing temporarily, unlink
if ( is_wp_error( $tmp ) ) {
@unlink($file_array['tmp_name']);
$file_array['tmp_name'] = '';
}

// do the validation and storage stuff
$id = media_handle_sideload( $file_array, $post->ID, NULL );
// If error storing permanently, unlink
if ( is_wp_error($id) ) {
@unlink($file_array['tmp_name']);
return $id;
}

// Set the featured image
set_post_thumbnail( $post->ID, $id );

}

}