Returns a string list with the final instance of $glue found substituted with $last - eg. "a, b, c, d, e" -> "a, b, c, d and e" if glue is ', ' and $last is ' and '.

str_list_ended.php

function str_list_ended($value, $glue = ', ', $last = ' and ') {
	return preg_replace(
		"/($glue)(?!.+$glue)/",
		$last,
		(is_array($value) ? implode($glue, $value) : $value)
	);
}