ขอแปะไว้ก่อนแล้วกัน ไม่มีเวลา
function catch_that_image() {
global $post, $posts;
$first_img = '';
$new_img_tag = "";
$output = preg_match_all('//i', $post->post_content, $matches);
$first_img = $matches [1] [0];
if(empty($first_img)){
$new_img_tag = "";
}
else{
echo $new_img_tag = "";
}
return $new_img_tag;
}