How to use post title as featured image's alt text in Wordpress?

No need to change WordPress core files:)

Just locate in your theme where the_post_thumbnail() function is used and change it to:

$title=get_the_title();the_post_thumbnail( array(150, 150),array( 'alt' =>$title) );

php image wordpress seo alt

user850010

You are absolutely right .

$title=get_the_title();the_post_thumbnail( array(150, 150),array( 'alt' =>$title) );

this is usefull of you Alex please check it out.

Alex , if you want to display only specific image then use this code

<img src="'.wp_get_attachment_url( get_post_thumbnail_id($item->ID)).'" alt="'.$item->post_title.'" title="'.$item->post_title.'" />

CodeHunter