$re = '/^\[([^\]]+)\] \[(오[전후] \d{1,2}:\d{2})\] (.*)$/m';
$str = '[철수] [오전 2:06] 메세지본문
위와 같은 문자열에서 사람이름, 시간, 메세지 본문을 따로 뽑아오고싶은데 정규표현식을 제대로 다뤄본적이 없어 고전중입니다 ㅠㅠ';
$subst = "$3 - $2, $1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php