I've read how accented characters might sometimes match [a-z]. What I'd like to know is how I could match a specific accented character. Obviously, preg_match('/[ñ]/', 'ñ') does not work.
Use the /u modifier. That will enable Unicode for the regexes. http://php.net/manual/en/reference.pcre.pattern.modifiers.php
You can take their codes and match them like \xD0 - heximal sequences if accented symbols are not accepted
来源：https://stackoverflow.com/questions/2250567/how-do-i-match-accented-characters-in-preg-match