List all existing custom post types in Wordpress.

PHP

<?php

    /**
     * Template Name: Custom Post Types List
     */

    get_header();

    $args=array(
        'public'                => true,
        'exclude_from_search'   => false,
        '_builtin'              => false
    ); 

    $output = 'names'; // names or objects, note names is the default
    $operator = 'and'; // 'and' or 'or'
    $post_types = get_post_types($args,$output,$operator);

    $posttypes_array = array();

    foreach ($post_types  as $post_type ) {
        $posttypes_array[] = $post_type;
    }

    echo "<pre>";
    print_r($posttypes_array);
    echo "</pre>";

    get_footer();

?>