Taxonomy/Post URL Rewrite rule example for WordPress

cpt.php

function my_rewrite_rules( $rules_array ) {
		$new = array();


		//get the list of categories and create a rewrite rules for each.
        // We get them in order by parent so that we can quickly build the array we need.
        $cats = get_terms( array( 'taxonomy' => 'category', 'hide_empty' => false, 'hierarchical' => true, 'fields' => 'all', 'orderby' => 'parent'));

        // extract the parents and build the array for generating the rules
        $cr = array();
        foreach ($cats as $c) {
            $cr[$c->term_id] = array('slug' => $c->slug, 'rewrite' => 2);
        }

        // set up the children that will be rewritten.
        foreach($cats as $c){
            if ( $c->parent != 0 || $c->slug === 'archive' ||  $c->slug === 'other-languages') {
               // $cr[$c->term_id] = array( 'slug' => $cr[$c->parent]['slug'] . '/' . $c->slug, 'rewrite' => 1);
                $cr[$c->term_id] = array( 'slug' => $c->slug, 'rewrite' => 1);
            }
        }


        foreach ($cr as $c){
            if ($c['rewrite'] == 1) {
                $match = '^' . $c['slug'] . '/(.+)?$';
                $new[$match] = 'index.php?cpt_slug=$matches[1]';
            }
        }

       

		return array_merge( $new, $rules_array );
	}