From WP StackExchange: http://wordpress.stackexchange.com/questions/90066/numbering-sections-and-block-level-elements-in-wpautop-wordpress-as-cms-for-l I am starting to learn how to write plugins for Wordpress. I'm interested in using WP as a CMS for long essays (6000-9000 words or more). My problem is what I call the Kindle problem, which is ho…

WP_autoaddparagraphanchor

class InsertAnchors {
    protected $count = 0;
    protected $links = '';
    public function build( $pattern, $content ) {
        $this->count = 0;
        $this->links = '';
        $content = preg_replace_callback( $pattern, array( $this, '_replacer' ), $content );
        return '<p>' . $this->links . '</p>' . $content;
    }
    public function _replacer( $matches ) {
        $this->count++;
        $this->links .= '<a href="#section_' . $this->count . '">Section ' . $this->count . '</a><br>';
        return '<p><a name="section_' . $this->count . '"></a>';
    }
}

function anchors_content_filter( $content ){
    $insert = new InsertAnchors();
    return $insert->build( '~<p>~', $content );
}
add_filter( 'the_content', 'anchors_content_filter', 100 );