Shorten text without braking words

/*
returns text limited by a specified length of characters but keeping words intact. the final character count will not be exact since it is affected by the possible removing of the a long word or by the addition of the ellipsis.
 
paramaters: 
	string - the input string
	chars - the length of characters wanted
	elli - the ellipsis to be used, defaults to '...'
*/
 
function shorten($string='', $chars=20, $elli='...'){
	list($new_string, $elli)= explode("\n", wordwrap($string, $chars, "\n", false));
	return  ( $elli ) ? $new_string.'...' : $new_string;
}