Get all users registered between two dates

wp-user-registration-query.php

<?php	
        /*
	 * Get all users registered after $start and before $end (dates in yyyy-mm-dd format)
	 *
	 * Based on my answer to this question: http://wordpress.stackexchange.com/questions/51485/how-can-i-query-all-users-who-registered-today/51492#51492
	 *
	 * @param (string) $start - start date in yyyy-mm-dd format
	 * @param (string) $end - end date in yyyy-mm-dd format
	 */

    function wpse51485_get_users_registered($start='', $end='' ){
		global $wpdb;

		if( empty($start) )
			$date = date('Y-m-d');

		if ( empty($end) )
			$end = $start;

		//Should probably validate input and throw up error. In any case, the following ensures the query is safe.

		$start_dt = new DateTime($start. ' 00:00:00');
		$s = $start_dt->format('Y-m-d H:i:s');

		$end_dt = new DateTime($end.' 23:59:59');
		$e = $end_dt->format('Y-m-d H:i:s');

		$sql = $wpdb->prepare("SELECT wp_users.* FROM wp_users WHERE 1=1 AND CAST(user_registered AS DATE) BETWEEN %s AND %s ORDER BY user_login ASC",$s,$e);

		$users = $wpdb->get_results($sql);

		return $users;
     }
?>