The meaning of /u, /i, /s in preg_match regular matching in PHP

What does /u /i /s mean by preg_match in PHP?
/u means matching according to unicode (utf-8) (mainly for multi-bytes such as Chinese characters)
/i means no size distinction Write (if there is a in the expression, then A is also the matching object)
/s means treating the string as a single line to match

More /u, /i, in preg_match regular matching in PHP For articles related to the meaning of /s, please pay attention to the PHP Chinese website!