Tweaking auto alt tag generation in Wordpress

[popokolok]

Hello,

I tried many WP plugins to create automatic alt tags site-wide. None of the available plugins seem to work (I Tried SEO Friendly Images, Wordpress SEO Images, WP Image SEO) even with the default theme... Any other plugins anyone can suggest, please?

Anyway, I found this code that's supposed to go into the functions.php of the theme, but it doesn't seem to work... It's supposed to check for images without an alt tag and fill in the post title - can anyone here please help me with making this code to change ALL alt tags by putting the post title in them and making this code work in the first place..?

function add_alt_tags($content)
{
        global $post;
        preg_match_all('/<img (.*?)\/>/', $content, $images);
        if(!is_null($images))
        {
                foreach($images[1] as $index => $value)
                {
                        if(!preg_match('/alt=/', $value))
                        {
                                $new_img = str_replace('<img', '<img alt="'.$post->post_title.'"', $images[0][$index]);
                                $content = str_replace($images[0][$index], $new_img, $content);
                        }
                }
        }
        return $content;
}
add_filter('the_content', 'add_alt_tags', 99999);

Thank you very much!