Whats wrong with my code? Need To add String to shortcode? [closed]

$special_id = ' . do_shortcode('[url_path_number]')' ;

Is completely wrong. do_shortcode() is a function and shouldn’t be inside quotes, because that just makes a string that says “do_shortcode()”. I don’t even know what you’re trying to do with the dot at the beginning.

$special_id = do_shortcode('[url_path_number]');

Is correct.