How to write "alt" tag in image for wordpress code?

Question

I want to use the code <img class="img-responsive" src="<?php echo the_post_thumbnail_url(); ?>" alt="" /> instead of <?php the_post_thumbnail(); ?>, to output the post thumbnail. Now, how can I get "alt" and "title" dynamically for post thumbnail. Is there any function provided by wordpress for this. I looked for a function from wordpress codex/developer site for this problem but I didn't find one.

Answer 1

Why would you want to avoid the_postthumbnail? It can give you the exact html you want if you use the right attributes. Anyway, you can access the title and alt tags of an image like this:

// get the ID of the featured image
$thumbnail_id = get_post_thumbnail_id( $post_id );
// retrieve title (an image is a post, so you can access the title as if it is a post title)
$title = get_post($thumbnail_id())->post_title;
// retrieve alt (which is stored as metadata to a post)
$alt = get_post_meta($thumbnail_id, '_wp_attachment_image_alt', true);